Group crypto_types

group crypto_types

Defines

PSA_KEY_TYPE_DSA_PUBLIC_KEY

DSA public key.

The import and export format is the representation of the public key y = g^x mod p as a big-endian byte string. The length of the byte string is the length of the base prime p in bytes.

PSA_KEY_TYPE_DSA_KEY_PAIR

DSA key pair (private and public key).

The import and export format is the representation of the private key x as a big-endian byte string. The length of the byte string is the private key size in bytes (leading zeroes are not stripped).

Deterministic DSA key derivation with psa_generate_derived_key follows FIPS 186-4 B.1.2: interpret the byte string as integer in big-endian order. Discard it if it is not in the range [0, N - 2] where N is the boundary of the private key domain (the prime p for Diffie-Hellman, the subprime q for DSA, or the order of the curve’s base point for ECC). Add 1 to the resulting integer and use this as the private key x.

PSA_KEY_TYPE_IS_DSA(type)

Whether a key type is a DSA key (pair or public-only).

PSA_ALG_DSA_BASE
PSA_ALG_DSA(hash_alg)

DSA signature with hashing.

This is the signature scheme defined by FIPS 186-4, with a random per-message secret number (k).

Parameters

  • hash_alg – A hash algorithm (PSA_ALG_XXX value such that PSA_ALG_IS_HASH(hash_alg) is true). This includes PSA_ALG_ANY_HASH when specifying the algorithm in a usage policy.

Returns

The corresponding DSA signature algorithm.

Returns

Unspecified if hash_alg is not a supported hash algorithm.

PSA_ALG_DETERMINISTIC_DSA_BASE
PSA_ALG_DSA_DETERMINISTIC_FLAG
PSA_ALG_DETERMINISTIC_DSA(hash_alg)

Deterministic DSA signature with hashing.

This is the deterministic variant defined by RFC 6979 of the signature scheme defined by FIPS 186-4.

Parameters

  • hash_alg – A hash algorithm (PSA_ALG_XXX value such that PSA_ALG_IS_HASH(hash_alg) is true). This includes PSA_ALG_ANY_HASH when specifying the algorithm in a usage policy.

Returns

The corresponding DSA signature algorithm.

Returns

Unspecified if hash_alg is not a supported hash algorithm.

PSA_ALG_IS_DSA(alg)
PSA_ALG_DSA_IS_DETERMINISTIC(alg)
PSA_ALG_IS_DETERMINISTIC_DSA(alg)
PSA_ALG_IS_RANDOMIZED_DSA(alg)
PSA_ALG_IS_VENDOR_HASH_AND_SIGN(alg)
PSA_ALG_CATEGORY_PAKE
PSA_ALG_IS_PAKE(alg)

Whether the specified algorithm is a password-authenticated key exchange.

Parameters
Returns

1 if alg is a password-authenticated key exchange (PAKE) algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported algorithm identifier.

PSA_ALG_JPAKE

The Password-authenticated key exchange by juggling (J-PAKE) algorithm.

This is J-PAKE as defined by RFC 8236, instantiated with the following parameters:

  • The group can be either an elliptic curve or defined over a finite field.

  • Schnorr NIZK proof as defined by RFC 8235 and using the same group as the J-PAKE algorithm.

  • A cryptographic hash function.

To select these parameters and set up the cipher suite, call these functions in any order:

psa_pake_cs_set_algorithm(cipher_suite, PSA_ALG_JPAKE);
psa_pake_cs_set_primitive(cipher_suite,
                          PSA_PAKE_PRIMITIVE(type, family, bits));
psa_pake_cs_set_hash(cipher_suite, hash);

For more information on how to set a specific curve or field, refer to the documentation of the individual PSA_PAKE_PRIMITIVE_TYPE_XXX constants.

After initializing a J-PAKE operation, call

psa_pake_setup(operation, cipher_suite);
psa_pake_set_user(operation, ...);
psa_pake_set_peer(operation, ...);
psa_pake_set_password_key(operation, ...);

The password is provided as a key. This can be the password text itself, in an agreed character encoding, or some value derived from the password as required by a higher level protocol.

(The implementation converts the key material to a number as described in Section 2.3.8 of SEC 1: Elliptic Curve Cryptography (https://www.secg.org/sec1-v2.pdf), before reducing it modulo q. Here q is order of the group defined by the primitive set in the cipher suite. The psa_pake_set_password_key() function returns an error if the result of the reduction is 0.)

The key exchange flow for J-PAKE is as follows:

  1. To get the first round data that needs to be sent to the peer, call 

    // Get g1
psa_pake_output(operation, #PSA_PAKE_STEP_KEY_SHARE, ...);
// Get the ZKP public key for x1
psa_pake_output(operation, #PSA_PAKE_STEP_ZK_PUBLIC, ...);
// Get the ZKP proof for x1
psa_pake_output(operation, #PSA_PAKE_STEP_ZK_PROOF, ...);
// Get g2
psa_pake_output(operation, #PSA_PAKE_STEP_KEY_SHARE, ...);
// Get the ZKP public key for x2
psa_pake_output(operation, #PSA_PAKE_STEP_ZK_PUBLIC, ...);
// Get the ZKP proof for x2
psa_pake_output(operation, #PSA_PAKE_STEP_ZK_PROOF, ...);

  2. To provide the first round data received from the peer to the operation, call 

    // Set g3
psa_pake_input(operation, #PSA_PAKE_STEP_KEY_SHARE, ...);
// Set the ZKP public key for x3
psa_pake_input(operation, #PSA_PAKE_STEP_ZK_PUBLIC, ...);
// Set the ZKP proof for x3
psa_pake_input(operation, #PSA_PAKE_STEP_ZK_PROOF, ...);
// Set g4
psa_pake_input(operation, #PSA_PAKE_STEP_KEY_SHARE, ...);
// Set the ZKP public key for x4
psa_pake_input(operation, #PSA_PAKE_STEP_ZK_PUBLIC, ...);
// Set the ZKP proof for x4
psa_pake_input(operation, #PSA_PAKE_STEP_ZK_PROOF, ...);

  3. To get the second round data that needs to be sent to the peer, call 

    // Get A
psa_pake_output(operation, #PSA_PAKE_STEP_KEY_SHARE, ...);
// Get ZKP public key for x2*s
psa_pake_output(operation, #PSA_PAKE_STEP_ZK_PUBLIC, ...);
// Get ZKP proof for x2*s
psa_pake_output(operation, #PSA_PAKE_STEP_ZK_PROOF, ...);

  4. To provide the second round data received from the peer to the operation, call 

    // Set B
psa_pake_input(operation, #PSA_PAKE_STEP_KEY_SHARE, ...);
// Set ZKP public key for x4*s
psa_pake_input(operation, #PSA_PAKE_STEP_ZK_PUBLIC, ...);
// Set ZKP proof for x4*s
psa_pake_input(operation, #PSA_PAKE_STEP_ZK_PROOF, ...);

  5. To access the shared secret call 

    // Get Ka=Kb=K
psa_pake_get_implicit_key()

For more information consult the documentation of the individual PSA_PAKE_STEP_XXX constants.

At this point there is a cryptographic guarantee that only the authenticated party who used the same password is able to compute the key. But there is no guarantee that the peer is the party it claims to be and was able to do so.

That is, the authentication is only implicit (the peer is not authenticated at this point, and no action should be taken that assume that they are - like for example accessing restricted files).

To make the authentication explicit there are various methods, see Section 5 of RFC 8236 for two examples.

PSA_KEY_TYPE_NONE

An invalid key type value.

Zero is not the encoding of any key type.

PSA_KEY_TYPE_VENDOR_FLAG

Vendor-defined key type flag.

Key types defined by this standard will never have the PSA_KEY_TYPE_VENDOR_FLAG bit set. Vendors who define additional key types must use an encoding with the PSA_KEY_TYPE_VENDOR_FLAG bit set and should respect the bitwise structure used by standard encodings whenever practical.

PSA_KEY_TYPE_CATEGORY_MASK
PSA_KEY_TYPE_CATEGORY_RAW
PSA_KEY_TYPE_CATEGORY_SYMMETRIC
PSA_KEY_TYPE_CATEGORY_PUBLIC_KEY
PSA_KEY_TYPE_CATEGORY_KEY_PAIR
PSA_KEY_TYPE_CATEGORY_FLAG_PAIR
PSA_KEY_TYPE_IS_VENDOR_DEFINED(type)

Whether a key type is vendor-defined.

See also PSA_KEY_TYPE_VENDOR_FLAG.

PSA_KEY_TYPE_IS_UNSTRUCTURED(type)

Whether a key type is an unstructured array of bytes.

This encompasses both symmetric keys and non-key data.

PSA_KEY_TYPE_IS_ASYMMETRIC(type)

Whether a key type is asymmetric: either a key pair or a public key.

PSA_KEY_TYPE_IS_PUBLIC_KEY(type)

Whether a key type is the public part of a key pair.

PSA_KEY_TYPE_IS_KEY_PAIR(type)

Whether a key type is a key pair containing a private part and a public part.

PSA_KEY_TYPE_KEY_PAIR_OF_PUBLIC_KEY(type)

The key pair type corresponding to a public key type.

You may also pass a key pair type as type, it will be left unchanged.

Parameters

  • type – A public key type or key pair type.

Returns

The corresponding key pair type. If type is not a public key or a key pair, the return value is undefined.

PSA_KEY_TYPE_PUBLIC_KEY_OF_KEY_PAIR(type)

The public key type corresponding to a key pair type.

You may also pass a public key type as type, it will be left unchanged.

Parameters

  • type – A public key type or key pair type.

Returns

The corresponding public key type. If type is not a public key or a key pair, the return value is undefined.

PSA_KEY_TYPE_RAW_DATA

Raw data.

A “key” of this type cannot be used for any cryptographic operation. Applications may use this type to store arbitrary data in the keystore.

PSA_KEY_TYPE_HMAC

HMAC key.

The key policy determines which underlying hash algorithm the key can be used for.

HMAC keys should generally have the same size as the underlying hash. This size can be calculated with PSA_HASH_LENGTH(alg) where alg is the HMAC algorithm or the underlying hash algorithm.

PSA_KEY_TYPE_DERIVE

A secret for key derivation.

This key type is for high-entropy secrets only. For low-entropy secrets, PSA_KEY_TYPE_PASSWORD should be used instead.

These keys can be used as the PSA_KEY_DERIVATION_INPUT_SECRET or PSA_KEY_DERIVATION_INPUT_PASSWORD input of key derivation algorithms.

The key policy determines which key derivation algorithm the key can be used for.

PSA_KEY_TYPE_PASSWORD

A low-entropy secret for password hashing or key derivation.

This key type is suitable for passwords and passphrases which are typically intended to be memorizable by humans, and have a low entropy relative to their size. It can be used for randomly generated or derived keys with maximum or near-maximum entropy, but PSA_KEY_TYPE_DERIVE is more suitable for such keys. It is not suitable for passwords with extremely low entropy, such as numerical PINs.

These keys can be used as the PSA_KEY_DERIVATION_INPUT_PASSWORD input of key derivation algorithms. Algorithms that accept such an input were designed to accept low-entropy secret and are known as password hashing or key stretching algorithms.

These keys cannot be used as the PSA_KEY_DERIVATION_INPUT_SECRET input of key derivation algorithms, as the algorithms that take such an input expect it to be high-entropy.

The key policy determines which key derivation algorithm the key can be used for, among the permissible subset defined above.

PSA_KEY_TYPE_PASSWORD_HASH

A secret value that can be used to verify a password hash.

The key policy determines which key derivation algorithm the key can be used for, among the same permissible subset as for PSA_KEY_TYPE_PASSWORD.

PSA_KEY_TYPE_PEPPER

A secret value that can be used in when computing a password hash.

The key policy determines which key derivation algorithm the key can be used for, among the subset of algorithms that can use pepper.

PSA_KEY_TYPE_AES

Key for a cipher, AEAD or MAC algorithm based on the AES block cipher.

The size of the key can be 16 bytes (AES-128), 24 bytes (AES-192) or 32 bytes (AES-256).

PSA_KEY_TYPE_ARIA

Key for a cipher, AEAD or MAC algorithm based on the ARIA block cipher.

PSA_KEY_TYPE_DES

Key for a cipher or MAC algorithm based on DES or 3DES (Triple-DES).

The size of the key can be 64 bits (single DES), 128 bits (2-key 3DES) or 192 bits (3-key 3DES).

Note that single DES and 2-key 3DES are weak and strongly deprecated and should only be used to decrypt legacy data. 3-key 3DES is weak and deprecated and should only be used in legacy protocols.

PSA_KEY_TYPE_CAMELLIA

Key for a cipher, AEAD or MAC algorithm based on the Camellia block cipher.

PSA_KEY_TYPE_CHACHA20

Key for the ChaCha20 stream cipher or the Chacha20-Poly1305 AEAD algorithm.

ChaCha20 and the ChaCha20_Poly1305 construction are defined in RFC 7539.

Note

For ChaCha20 and ChaCha20_Poly1305, Mbed TLS only supports 12-byte nonces.

Note

For ChaCha20, the initial counter value is 0. To encrypt or decrypt with the initial counter value 1, you can process and discard a 64-byte block before the real data.

PSA_KEY_TYPE_RSA_PUBLIC_KEY

RSA public key.

The size of an RSA key is the bit size of the modulus.

PSA_KEY_TYPE_RSA_KEY_PAIR

RSA key pair (private and public key).

The size of an RSA key is the bit size of the modulus.

PSA_KEY_TYPE_IS_RSA(type)

Whether a key type is an RSA key (pair or public-only).

PSA_KEY_TYPE_ECC_PUBLIC_KEY_BASE
PSA_KEY_TYPE_ECC_KEY_PAIR_BASE
PSA_KEY_TYPE_ECC_CURVE_MASK
PSA_KEY_TYPE_ECC_KEY_PAIR(curve)

Elliptic curve key pair.

The size of an elliptic curve key is the bit size associated with the curve, i.e. the bit size of q for a curve over a field F. See the documentation of PSA_ECC_FAMILY_xxx curve families for details.

Parameters

  • curve – A value of type psa_ecc_family_t that identifies the ECC curve to be used.

PSA_KEY_TYPE_ECC_PUBLIC_KEY(curve)

Elliptic curve public key.

The size of an elliptic curve public key is the same as the corresponding private key (see PSA_KEY_TYPE_ECC_KEY_PAIR and the documentation of PSA_ECC_FAMILY_xxx curve families).

Parameters

  • curve – A value of type psa_ecc_family_t that identifies the ECC curve to be used.

PSA_KEY_TYPE_IS_ECC(type)

Whether a key type is an elliptic curve key (pair or public-only).

PSA_KEY_TYPE_IS_ECC_KEY_PAIR(type)

Whether a key type is an elliptic curve key pair.

PSA_KEY_TYPE_IS_ECC_PUBLIC_KEY(type)

Whether a key type is an elliptic curve public key.

PSA_KEY_TYPE_ECC_GET_FAMILY(type)

Extract the curve from an elliptic curve key type.

PSA_ECC_FAMILY_IS_WEIERSTRASS(family)

Check if the curve of given family is Weierstrass elliptic curve.

PSA_ECC_FAMILY_SECP_K1

SEC Koblitz curves over prime fields.

This family comprises the following curves: secp192k1, secp224k1, secp256k1. They are defined in Standards for Efficient Cryptography, SEC 2: Recommended Elliptic Curve Domain Parameters. https://www.secg.org/sec2-v2.pdf

Note

For secp224k1, the bit-size is 225 (size of a private value).

Note

Mbed TLS only supports secp192k1 and secp256k1.

PSA_ECC_FAMILY_SECP_R1

SEC random curves over prime fields.

This family comprises the following curves: secp192r1, secp224r1, secp256r1, secp384r1, secp521r1. They are defined in Standards for Efficient Cryptography, SEC 2: Recommended Elliptic Curve Domain Parameters. https://www.secg.org/sec2-v2.pdf

PSA_ECC_FAMILY_SECP_R2
PSA_ECC_FAMILY_SECT_K1

SEC Koblitz curves over binary fields.

This family comprises the following curves: sect163k1, sect233k1, sect239k1, sect283k1, sect409k1, sect571k1. They are defined in Standards for Efficient Cryptography, SEC 2: Recommended Elliptic Curve Domain Parameters. https://www.secg.org/sec2-v2.pdf

Note

Mbed TLS does not support any curve in this family.

PSA_ECC_FAMILY_SECT_R1

SEC random curves over binary fields.

This family comprises the following curves: sect163r1, sect233r1, sect283r1, sect409r1, sect571r1. They are defined in Standards for Efficient Cryptography, SEC 2: Recommended Elliptic Curve Domain Parameters. https://www.secg.org/sec2-v2.pdf

Note

Mbed TLS does not support any curve in this family.

PSA_ECC_FAMILY_SECT_R2

SEC additional random curves over binary fields.

This family comprises the following curve: sect163r2. It is defined in Standards for Efficient Cryptography, SEC 2: Recommended Elliptic Curve Domain Parameters. https://www.secg.org/sec2-v2.pdf

Note

Mbed TLS does not support any curve in this family.

PSA_ECC_FAMILY_BRAINPOOL_P_R1

Brainpool P random curves.

This family comprises the following curves: brainpoolP160r1, brainpoolP192r1, brainpoolP224r1, brainpoolP256r1, brainpoolP320r1, brainpoolP384r1, brainpoolP512r1. It is defined in RFC 5639.

Note

Mbed TLS only supports the 256-bit, 384-bit and 512-bit curves in this family.

PSA_ECC_FAMILY_MONTGOMERY

Curve25519 and Curve448.

This family comprises the following Montgomery curves:

  • 255-bit: Bernstein et al., Curve25519: new Diffie-Hellman speed records, LNCS 3958, 2006. The algorithm PSA_ALG_ECDH performs X25519 when used with this curve.

  • 448-bit: Hamburg, Ed448-Goldilocks, a new elliptic curve, NIST ECC Workshop, 2015. The algorithm PSA_ALG_ECDH performs X448 when used with this curve.

PSA_ECC_FAMILY_TWISTED_EDWARDS

The twisted Edwards curves Ed25519 and Ed448.

These curves are suitable for EdDSA (PSA_ALG_PURE_EDDSA for both curves, PSA_ALG_ED25519PH for the 255-bit curve, PSA_ALG_ED448PH for the 448-bit curve).

This family comprises the following twisted Edwards curves:

  • 255-bit: Edwards25519, the twisted Edwards curve birationally equivalent to Curve25519. Bernstein et al., Twisted Edwards curves, Africacrypt 2008.

  • 448-bit: Edwards448, the twisted Edwards curve birationally equivalent to Curve448. Hamburg, Ed448-Goldilocks, a new elliptic curve, NIST ECC Workshop, 2015.

Note

Mbed TLS does not support Edwards curves yet.

PSA_KEY_TYPE_DH_PUBLIC_KEY_BASE
PSA_KEY_TYPE_DH_KEY_PAIR_BASE
PSA_KEY_TYPE_DH_GROUP_MASK
PSA_KEY_TYPE_DH_KEY_PAIR(group)

Diffie-Hellman key pair.

Parameters

  • group – A value of type psa_dh_family_t that identifies the Diffie-Hellman group to be used.

PSA_KEY_TYPE_DH_PUBLIC_KEY(group)

Diffie-Hellman public key.

Parameters

  • group – A value of type psa_dh_family_t that identifies the Diffie-Hellman group to be used.

PSA_KEY_TYPE_IS_DH(type)

Whether a key type is a Diffie-Hellman key (pair or public-only).

PSA_KEY_TYPE_IS_DH_KEY_PAIR(type)

Whether a key type is a Diffie-Hellman key pair.

PSA_KEY_TYPE_IS_DH_PUBLIC_KEY(type)

Whether a key type is a Diffie-Hellman public key.

PSA_KEY_TYPE_DH_GET_FAMILY(type)

Extract the group from a Diffie-Hellman key type.

PSA_DH_FAMILY_RFC7919

Diffie-Hellman groups defined in RFC 7919 Appendix A.

This family includes groups with the following key sizes (in bits): 2048, 3072, 4096, 6144, 8192. A given implementation may support all of these sizes or only a subset.

PSA_GET_KEY_TYPE_BLOCK_SIZE_EXPONENT(type)
PSA_BLOCK_CIPHER_BLOCK_LENGTH(type)

The block size of a block cipher.

Note

It is possible to build stream cipher algorithms on top of a block cipher, for example CTR mode (PSA_ALG_CTR). This macro only takes the key type into account, so it cannot be used to determine the size of the data that psa_cipher_update() might buffer for future processing in general.

Note

This macro returns a compile-time constant if its argument is one.

Warning

This macro may evaluate its argument multiple times.

Parameters
Returns

The block size for a block cipher, or 1 for a stream cipher. The return value is undefined if type is not a supported cipher key type.

PSA_ALG_VENDOR_FLAG

Vendor-defined algorithm flag.

Algorithms defined by this standard will never have the PSA_ALG_VENDOR_FLAG bit set. Vendors who define additional algorithms must use an encoding with the PSA_ALG_VENDOR_FLAG bit set and should respect the bitwise structure used by standard encodings whenever practical.

PSA_ALG_CATEGORY_MASK
PSA_ALG_CATEGORY_HASH
PSA_ALG_CATEGORY_MAC
PSA_ALG_CATEGORY_CIPHER
PSA_ALG_CATEGORY_AEAD
PSA_ALG_CATEGORY_SIGN
PSA_ALG_CATEGORY_ASYMMETRIC_ENCRYPTION
PSA_ALG_CATEGORY_KEY_DERIVATION
PSA_ALG_CATEGORY_KEY_AGREEMENT
PSA_ALG_IS_VENDOR_DEFINED(alg)

Whether an algorithm is vendor-defined.

See also PSA_ALG_VENDOR_FLAG.

PSA_ALG_IS_HASH(alg)

Whether the specified algorithm is a hash algorithm.

Parameters
Returns

1 if alg is a hash algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported algorithm identifier.

PSA_ALG_IS_MAC(alg)

Whether the specified algorithm is a MAC algorithm.

Parameters
Returns

1 if alg is a MAC algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported algorithm identifier.

PSA_ALG_IS_CIPHER(alg)

Whether the specified algorithm is a symmetric cipher algorithm.

Parameters
Returns

1 if alg is a symmetric cipher algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported algorithm identifier.

PSA_ALG_IS_AEAD(alg)

Whether the specified algorithm is an authenticated encryption with associated data (AEAD) algorithm.

Parameters
Returns

1 if alg is an AEAD algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported algorithm identifier.

PSA_ALG_IS_SIGN(alg)

Whether the specified algorithm is an asymmetric signature algorithm, also known as public-key signature algorithm.

Parameters
Returns

1 if alg is an asymmetric signature algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported algorithm identifier.

PSA_ALG_IS_ASYMMETRIC_ENCRYPTION(alg)

Whether the specified algorithm is an asymmetric encryption algorithm, also known as public-key encryption algorithm.

Parameters
Returns

1 if alg is an asymmetric encryption algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported algorithm identifier.

PSA_ALG_IS_KEY_AGREEMENT(alg)

Whether the specified algorithm is a key agreement algorithm.

Parameters
Returns

1 if alg is a key agreement algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported algorithm identifier.

PSA_ALG_IS_KEY_DERIVATION(alg)

Whether the specified algorithm is a key derivation algorithm.

Parameters
Returns

1 if alg is a key derivation algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported algorithm identifier.

PSA_ALG_IS_KEY_DERIVATION_STRETCHING(alg)

Whether the specified algorithm is a key stretching / password hashing algorithm.

A key stretching / password hashing algorithm is a key derivation algorithm that is suitable for use with a low-entropy secret such as a password. Equivalently, it’s a key derivation algorithm that uses a PSA_KEY_DERIVATION_INPUT_PASSWORD input step.

Parameters
Returns

1 if alg is a key stretching / password hashing algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported algorithm identifier.

PSA_ALG_NONE

An invalid algorithm identifier value.

PSA_ALG_HASH_MASK
PSA_ALG_MD5

MD5

PSA_ALG_RIPEMD160

PSA_ALG_RIPEMD160

PSA_ALG_SHA_1

SHA1

PSA_ALG_SHA_224

SHA2-224

PSA_ALG_SHA_256

SHA2-256

PSA_ALG_SHA_384

SHA2-384

PSA_ALG_SHA_512

SHA2-512

PSA_ALG_SHA_512_224

SHA2-512/224

PSA_ALG_SHA_512_256

SHA2-512/256

PSA_ALG_SHA3_224

SHA3-224

PSA_ALG_SHA3_256

SHA3-256

PSA_ALG_SHA3_384

SHA3-384

PSA_ALG_SHA3_512

SHA3-512

PSA_ALG_SHAKE256_512

The first 512 bits (64 bytes) of the SHAKE256 output.

This is the prehashing for Ed448ph (see PSA_ALG_ED448PH). For other scenarios where a hash function based on SHA3/SHAKE is desired, SHA3-512 has the same output size and a (theoretically) higher security strength.

PSA_ALG_ANY_HASH

In a hash-and-sign algorithm policy, allow any hash algorithm.

This value may be used to form the algorithm usage field of a policy for a signature algorithm that is parametrized by a hash. The key may then be used to perform operations using the same signature algorithm parametrized with any supported hash.

That is, suppose that PSA_xxx_SIGNATURE is one of the following macros:

  • PSA_ALG_RSA_PKCS1V15_SIGN, PSA_ALG_RSA_PSS, PSA_ALG_RSA_PSS_ANY_SALT,

  • PSA_ALG_ECDSA, PSA_ALG_DETERMINISTIC_ECDSA. Then you may create and use a key as follows:

  • Set the key usage field using PSA_ALG_ANY_HASH, for example: 

    psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_SIGN_HASH); // or VERIFY
psa_set_key_algorithm(&attributes, PSA_xxx_SIGNATURE(PSA_ALG_ANY_HASH));

  • Import or generate key material.

  • Call psa_sign_hash() or psa_verify_hash(), passing an algorithm built from PSA_xxx_SIGNATURE and a specific hash. Each call to sign or verify a message may use a different hash. 

    psa_sign_hash(key, PSA_xxx_SIGNATURE(PSA_ALG_SHA_256), ...);
psa_sign_hash(key, PSA_xxx_SIGNATURE(PSA_ALG_SHA_512), ...);
psa_sign_hash(key, PSA_xxx_SIGNATURE(PSA_ALG_SHA3_256), ...);

This value may not be used to build other algorithms that are parametrized over a hash. For any valid use of this macro to build an algorithm alg, PSA_ALG_IS_HASH_AND_SIGN(alg) is true.

This value may not be used to build an algorithm specification to perform an operation. It is only valid to build policies.

PSA_ALG_MAC_SUBCATEGORY_MASK
PSA_ALG_HMAC_BASE
PSA_ALG_HMAC(hash_alg)

Macro to build an HMAC algorithm.

For example, PSA_ALG_HMAC(PSA_ALG_SHA_256) is HMAC-SHA-256.

Parameters

  • hash_alg – A hash algorithm (PSA_ALG_XXX value such that PSA_ALG_IS_HASH(hash_alg) is true).

Returns

The corresponding HMAC algorithm.

Returns

Unspecified if hash_alg is not a supported hash algorithm.

PSA_ALG_HMAC_GET_HASH(hmac_alg)
PSA_ALG_IS_HMAC(alg)

Whether the specified algorithm is an HMAC algorithm.

HMAC is a family of MAC algorithms that are based on a hash function.

Parameters
Returns

1 if alg is an HMAC algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported algorithm identifier.

PSA_ALG_MAC_TRUNCATION_MASK
PSA_MAC_TRUNCATION_OFFSET
PSA_ALG_MAC_AT_LEAST_THIS_LENGTH_FLAG
PSA_ALG_TRUNCATED_MAC(mac_alg, mac_length)

Macro to build a truncated MAC algorithm.

A truncated MAC algorithm is identical to the corresponding MAC algorithm except that the MAC value for the truncated algorithm consists of only the first mac_length bytes of the MAC value for the untruncated algorithm.

Note

This macro may allow constructing algorithm identifiers that are not valid, either because the specified length is larger than the untruncated MAC or because the specified length is smaller than permitted by the implementation.

Note

It is implementation-defined whether a truncated MAC that is truncated to the same length as the MAC of the untruncated algorithm is considered identical to the untruncated algorithm for policy comparison purposes.

Parameters

  • mac_alg – A MAC algorithm identifier (value of type psa_algorithm_t such that PSA_ALG_IS_MAC(mac_alg) is true). This may be a truncated or untruncated MAC algorithm.

  • mac_length – Desired length of the truncated MAC in bytes. This must be at most the full length of the MAC and must be at least an implementation-specified minimum. The implementation-specified minimum shall not be zero.

Returns

The corresponding MAC algorithm with the specified length.

Returns

Unspecified if mac_alg is not a supported MAC algorithm or if mac_length is too small or too large for the specified MAC algorithm.

PSA_ALG_FULL_LENGTH_MAC(mac_alg)

Macro to build the base MAC algorithm corresponding to a truncated MAC algorithm.

Parameters

  • mac_alg – A MAC algorithm identifier (value of type psa_algorithm_t such that PSA_ALG_IS_MAC(mac_alg) is true). This may be a truncated or untruncated MAC algorithm.

Returns

The corresponding base MAC algorithm.

Returns

Unspecified if mac_alg is not a supported MAC algorithm.

PSA_MAC_TRUNCATED_LENGTH(mac_alg)

Length to which a MAC algorithm is truncated.

Parameters
Returns

Length of the truncated MAC in bytes.

Returns

0 if mac_alg is a non-truncated MAC algorithm.

Returns

Unspecified if mac_alg is not a supported MAC algorithm.

PSA_ALG_AT_LEAST_THIS_LENGTH_MAC(mac_alg, min_mac_length)

Macro to build a MAC minimum-MAC-length wildcard algorithm.

A minimum-MAC-length MAC wildcard algorithm permits all MAC algorithms sharing the same base algorithm, and where the (potentially truncated) MAC length of the specific algorithm is equal to or larger then the wildcard algorithm’s minimum MAC length.

Note

When setting the minimum required MAC length to less than the smallest MAC length allowed by the base algorithm, this effectively becomes an ‘any-MAC-length-allowed’ policy for that base algorithm.

Parameters

  • mac_alg – A MAC algorithm identifier (value of type psa_algorithm_t such that PSA_ALG_IS_MAC(mac_alg) is true).

  • min_mac_length – Desired minimum length of the message authentication code in bytes. This must be at most the untruncated length of the MAC and must be at least 1.

Returns

The corresponding MAC wildcard algorithm with the specified minimum length.

Returns

Unspecified if mac_alg is not a supported MAC algorithm or if min_mac_length is less than 1 or too large for the specified MAC algorithm.

PSA_ALG_CIPHER_MAC_BASE
PSA_ALG_CBC_MAC

The CBC-MAC construction over a block cipher

Warning

CBC-MAC is insecure in many cases. A more secure mode, such as PSA_ALG_CMAC, is recommended.

PSA_ALG_CMAC

The CMAC construction over a block cipher

PSA_ALG_IS_BLOCK_CIPHER_MAC(alg)

Whether the specified algorithm is a MAC algorithm based on a block cipher.

Parameters
Returns

1 if alg is a MAC algorithm based on a block cipher, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported algorithm identifier.

PSA_ALG_CIPHER_STREAM_FLAG
PSA_ALG_CIPHER_FROM_BLOCK_FLAG
PSA_ALG_IS_STREAM_CIPHER(alg)

Whether the specified algorithm is a stream cipher.

A stream cipher is a symmetric cipher that encrypts or decrypts messages by applying a bitwise-xor with a stream of bytes that is generated from a key.

Parameters
Returns

1 if alg is a stream cipher algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported algorithm identifier or if it is not a symmetric cipher algorithm.

PSA_ALG_STREAM_CIPHER

The stream cipher mode of a stream cipher algorithm.

The underlying stream cipher is determined by the key type.

PSA_ALG_CTR

The CTR stream cipher mode.

CTR is a stream cipher which is built from a block cipher. The underlying block cipher is determined by the key type. For example, to use AES-128-CTR, use this algorithm with a key of type PSA_KEY_TYPE_AES and a length of 128 bits (16 bytes).

PSA_ALG_CFB

The CFB stream cipher mode.

The underlying block cipher is determined by the key type.

PSA_ALG_OFB

The OFB stream cipher mode.

The underlying block cipher is determined by the key type.

PSA_ALG_XTS

The XTS cipher mode.

XTS is a cipher mode which is built from a block cipher. It requires at least one full block of input, but beyond this minimum the input does not need to be a whole number of blocks.

PSA_ALG_ECB_NO_PADDING

The Electronic Code Book (ECB) mode of a block cipher, with no padding.

The underlying block cipher is determined by the key type.

This symmetric cipher mode can only be used with messages whose lengths are a multiple of the block size of the chosen block cipher.

ECB mode does not accept an initialization vector (IV). When using a multi-part cipher operation with this algorithm, psa_cipher_generate_iv() and psa_cipher_set_iv() must not be called.

Warning

ECB mode does not protect the confidentiality of the encrypted data except in extremely narrow circumstances. It is recommended that applications only use ECB if they need to construct an operating mode that the implementation does not provide. Implementations are encouraged to provide the modes that applications need in preference to supporting direct access to ECB.

PSA_ALG_CBC_NO_PADDING

The CBC block cipher chaining mode, with no padding.

The underlying block cipher is determined by the key type.

This symmetric cipher mode can only be used with messages whose lengths are whole number of blocks for the chosen block cipher.

PSA_ALG_CBC_PKCS7

The CBC block cipher chaining mode with PKCS#7 padding.

The underlying block cipher is determined by the key type.

This is the padding method defined by PKCS#7 (RFC 2315) 10.3.

PSA_ALG_AEAD_FROM_BLOCK_FLAG
PSA_ALG_IS_AEAD_ON_BLOCK_CIPHER(alg)

Whether the specified algorithm is an AEAD mode on a block cipher.

Parameters
Returns

1 if alg is an AEAD algorithm which is an AEAD mode based on a block cipher, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported algorithm identifier.

PSA_ALG_CCM

The CCM authenticated encryption algorithm.

The underlying block cipher is determined by the key type.

PSA_ALG_CCM_STAR_NO_TAG

The CCM* cipher mode without authentication.

This is CCM* as specified in IEEE 802.15.4 §7, with a tag length of 0. For CCM* with a nonzero tag length, use the AEAD algorithm PSA_ALG_CCM.

The underlying block cipher is determined by the key type.

Currently only 13-byte long IV’s are supported.

PSA_ALG_GCM

The GCM authenticated encryption algorithm.

The underlying block cipher is determined by the key type.

PSA_ALG_CHACHA20_POLY1305

The Chacha20-Poly1305 AEAD algorithm.

The ChaCha20_Poly1305 construction is defined in RFC 7539.

Implementations must support 12-byte nonces, may support 8-byte nonces, and should reject other sizes.

Implementations must support 16-byte tags and should reject other sizes.

PSA_ALG_AEAD_TAG_LENGTH_MASK
PSA_AEAD_TAG_LENGTH_OFFSET
PSA_ALG_AEAD_AT_LEAST_THIS_LENGTH_FLAG
PSA_ALG_AEAD_WITH_SHORTENED_TAG(aead_alg, tag_length)

Macro to build a shortened AEAD algorithm.

A shortened AEAD algorithm is similar to the corresponding AEAD algorithm, but has an authentication tag that consists of fewer bytes. Depending on the algorithm, the tag length may affect the calculation of the ciphertext.

Parameters

  • aead_alg – An AEAD algorithm identifier (value of type psa_algorithm_t such that PSA_ALG_IS_AEAD(aead_alg) is true).

  • tag_length – Desired length of the authentication tag in bytes.

Returns

The corresponding AEAD algorithm with the specified length.

Returns

Unspecified if aead_alg is not a supported AEAD algorithm or if tag_length is not valid for the specified AEAD algorithm.

PSA_ALG_AEAD_GET_TAG_LENGTH(aead_alg)

Retrieve the tag length of a specified AEAD algorithm

Parameters
Returns

The tag length specified by the input algorithm.

Returns

Unspecified if aead_alg is not a supported AEAD algorithm.

PSA_ALG_AEAD_WITH_DEFAULT_LENGTH_TAG(aead_alg)

Calculate the corresponding AEAD algorithm with the default tag length.

Parameters

  • aead_alg – An AEAD algorithm (PSA_ALG_XXX value such that PSA_ALG_IS_AEAD(aead_alg) is true).

Returns

The corresponding AEAD algorithm with the default tag length for that algorithm.

PSA_ALG_AEAD_WITH_DEFAULT_LENGTH_TAG_CASE(aead_alg, ref)
PSA_ALG_AEAD_WITH_AT_LEAST_THIS_LENGTH_TAG(aead_alg, min_tag_length)

Macro to build an AEAD minimum-tag-length wildcard algorithm.

A minimum-tag-length AEAD wildcard algorithm permits all AEAD algorithms sharing the same base algorithm, and where the tag length of the specific algorithm is equal to or larger then the minimum tag length specified by the wildcard algorithm.

Note

When setting the minimum required tag length to less than the smallest tag length allowed by the base algorithm, this effectively becomes an ‘any-tag-length-allowed’ policy for that base algorithm.

Parameters

  • aead_alg – An AEAD algorithm identifier (value of type psa_algorithm_t such that PSA_ALG_IS_AEAD(aead_alg) is true).

  • min_tag_length – Desired minimum length of the authentication tag in bytes. This must be at least 1 and at most the largest allowed tag length of the algorithm.

Returns

The corresponding AEAD wildcard algorithm with the specified minimum length.

Returns

Unspecified if aead_alg is not a supported AEAD algorithm or if min_tag_length is less than 1 or too large for the specified AEAD algorithm.

PSA_ALG_RSA_PKCS1V15_SIGN_BASE
PSA_ALG_RSA_PKCS1V15_SIGN(hash_alg)

RSA PKCS#1 v1.5 signature with hashing.

This is the signature scheme defined by RFC 8017 (PKCS#1: RSA Cryptography Specifications) under the name RSASSA-PKCS1-v1_5.

Parameters

  • hash_alg – A hash algorithm (PSA_ALG_XXX value such that PSA_ALG_IS_HASH(hash_alg) is true). This includes PSA_ALG_ANY_HASH when specifying the algorithm in a usage policy.

Returns

The corresponding RSA PKCS#1 v1.5 signature algorithm.

Returns

Unspecified if hash_alg is not a supported hash algorithm.

PSA_ALG_RSA_PKCS1V15_SIGN_RAW

Raw PKCS#1 v1.5 signature.

The input to this algorithm is the DigestInfo structure used by RFC 8017 (PKCS#1: RSA Cryptography Specifications), 9.2 steps 3—6.

PSA_ALG_IS_RSA_PKCS1V15_SIGN(alg)
PSA_ALG_RSA_PSS_BASE
PSA_ALG_RSA_PSS_ANY_SALT_BASE
PSA_ALG_RSA_PSS(hash_alg)

RSA PSS signature with hashing.

This is the signature scheme defined by RFC 8017 (PKCS#1: RSA Cryptography Specifications) under the name RSASSA-PSS, with the message generation function MGF1, and with a salt length equal to the length of the hash, or the largest possible salt length for the algorithm and key size if that is smaller than the hash length. The specified hash algorithm is used to hash the input message, to create the salted hash, and for the mask generation.

Parameters

  • hash_alg – A hash algorithm (PSA_ALG_XXX value such that PSA_ALG_IS_HASH(hash_alg) is true). This includes PSA_ALG_ANY_HASH when specifying the algorithm in a usage policy.

Returns

The corresponding RSA PSS signature algorithm.

Returns

Unspecified if hash_alg is not a supported hash algorithm.

PSA_ALG_RSA_PSS_ANY_SALT(hash_alg)

RSA PSS signature with hashing with relaxed verification.

This algorithm has the same behavior as PSA_ALG_RSA_PSS when signing, but allows an arbitrary salt length (including 0) when verifying a signature.

Parameters

  • hash_alg – A hash algorithm (PSA_ALG_XXX value such that PSA_ALG_IS_HASH(hash_alg) is true). This includes PSA_ALG_ANY_HASH when specifying the algorithm in a usage policy.

Returns

The corresponding RSA PSS signature algorithm.

Returns

Unspecified if hash_alg is not a supported hash algorithm.

PSA_ALG_IS_RSA_PSS_STANDARD_SALT(alg)

Whether the specified algorithm is RSA PSS with standard salt.

Parameters

  • alg – An algorithm value or an algorithm policy wildcard.

Returns

1 if alg is of the form PSA_ALG_RSA_PSS(hash_alg), where hash_alg is a hash algorithm or PSA_ALG_ANY_HASH. 0 otherwise. This macro may return either 0 or 1 if alg is not a supported algorithm identifier or policy.

PSA_ALG_IS_RSA_PSS_ANY_SALT(alg)

Whether the specified algorithm is RSA PSS with any salt.

Parameters

  • alg – An algorithm value or an algorithm policy wildcard.

Returns

1 if alg is of the form PSA_ALG_RSA_PSS_ANY_SALT_BASE(hash_alg), where hash_alg is a hash algorithm or PSA_ALG_ANY_HASH. 0 otherwise. This macro may return either 0 or 1 if alg is not a supported algorithm identifier or policy.

PSA_ALG_IS_RSA_PSS(alg)

Whether the specified algorithm is RSA PSS.

This includes any of the RSA PSS algorithm variants, regardless of the constraints on salt length.

Parameters

  • alg – An algorithm value or an algorithm policy wildcard.

Returns

1 if alg is of the form PSA_ALG_RSA_PSS(hash_alg) or PSA_ALG_RSA_PSS_ANY_SALT_BASE(hash_alg), where hash_alg is a hash algorithm or PSA_ALG_ANY_HASH. 0 otherwise. This macro may return either 0 or 1 if alg is not a supported algorithm identifier or policy.

PSA_ALG_ECDSA_BASE
PSA_ALG_ECDSA(hash_alg)

ECDSA signature with hashing.

This is the ECDSA signature scheme defined by ANSI X9.62, with a random per-message secret number (k).

The representation of the signature as a byte string consists of the concatenation of the signature values r and s. Each of r and s is encoded as an N-octet string, where N is the length of the base point of the curve in octets. Each value is represented in big-endian order (most significant octet first).

Parameters

  • hash_alg – A hash algorithm (PSA_ALG_XXX value such that PSA_ALG_IS_HASH(hash_alg) is true). This includes PSA_ALG_ANY_HASH when specifying the algorithm in a usage policy.

Returns

The corresponding ECDSA signature algorithm.

Returns

Unspecified if hash_alg is not a supported hash algorithm.

PSA_ALG_ECDSA_ANY

ECDSA signature without hashing.

This is the same signature scheme as PSA_ALG_ECDSA(), but without specifying a hash algorithm. This algorithm may only be used to sign or verify a sequence of bytes that should be an already-calculated hash. Note that the input is padded with zeros on the left or truncated on the left as required to fit the curve size.

PSA_ALG_DETERMINISTIC_ECDSA_BASE
PSA_ALG_DETERMINISTIC_ECDSA(hash_alg)

Deterministic ECDSA signature with hashing.

This is the deterministic ECDSA signature scheme defined by RFC 6979.

The representation of a signature is the same as with PSA_ALG_ECDSA().

Note that when this algorithm is used for verification, signatures made with randomized ECDSA (PSA_ALG_ECDSA(hash_alg)) with the same private key are accepted. In other words, PSA_ALG_DETERMINISTIC_ECDSA(hash_alg) differs from PSA_ALG_ECDSA(hash_alg) only for signature, not for verification.

Parameters

  • hash_alg – A hash algorithm (PSA_ALG_XXX value such that PSA_ALG_IS_HASH(hash_alg) is true). This includes PSA_ALG_ANY_HASH when specifying the algorithm in a usage policy.

Returns

The corresponding deterministic ECDSA signature algorithm.

Returns

Unspecified if hash_alg is not a supported hash algorithm.

PSA_ALG_ECDSA_DETERMINISTIC_FLAG
PSA_ALG_IS_ECDSA(alg)
PSA_ALG_ECDSA_IS_DETERMINISTIC(alg)
PSA_ALG_IS_DETERMINISTIC_ECDSA(alg)
PSA_ALG_IS_RANDOMIZED_ECDSA(alg)
PSA_ALG_PURE_EDDSA

Edwards-curve digital signature algorithm without prehashing (PureEdDSA), using standard parameters.

Contexts are not supported in the current version of this specification because there is no suitable signature interface that can take the context as a parameter. A future version of this specification may add suitable functions and extend this algorithm to support contexts.

PureEdDSA requires an elliptic curve key on a twisted Edwards curve. In this specification, the following curves are supported:

  • PSA_ECC_FAMILY_TWISTED_EDWARDS, 255-bit: Ed25519 as specified in RFC 8032. The curve is Edwards25519. The hash function used internally is SHA-512.

  • PSA_ECC_FAMILY_TWISTED_EDWARDS, 448-bit: Ed448 as specified in RFC 8032. The curve is Edwards448. The hash function used internally is the first 114 bytes of the SHAKE256 output.

This algorithm can be used with psa_sign_message() and psa_verify_message(). Since there is no prehashing, it cannot be used with psa_sign_hash() or psa_verify_hash().

The signature format is the concatenation of R and S as defined by RFC 8032 §5.1.6 and §5.2.6 (a 64-byte string for Ed25519, a 114-byte string for Ed448).

PSA_ALG_HASH_EDDSA_BASE
PSA_ALG_IS_HASH_EDDSA(alg)
PSA_ALG_ED25519PH

Edwards-curve digital signature algorithm with prehashing (HashEdDSA), using SHA-512 and the Edwards25519 curve.

See PSA_ALG_PURE_EDDSA regarding context support and the signature format.

This algorithm is Ed25519 as specified in RFC 8032. The curve is Edwards25519. The prehash is SHA-512. The hash function used internally is SHA-512.

This is a hash-and-sign algorithm: to calculate a signature, you can either:

PSA_ALG_ED448PH

Edwards-curve digital signature algorithm with prehashing (HashEdDSA), using SHAKE256 and the Edwards448 curve.

See PSA_ALG_PURE_EDDSA regarding context support and the signature format.

This algorithm is Ed448 as specified in RFC 8032. The curve is Edwards448. The prehash is the first 64 bytes of the SHAKE256 output. The hash function used internally is the first 114 bytes of the SHAKE256 output.

This is a hash-and-sign algorithm: to calculate a signature, you can either:

PSA_ALG_IS_VENDOR_HASH_AND_SIGN(alg)
PSA_ALG_IS_SIGN_HASH(alg)

Whether the specified algorithm is a signature algorithm that can be used with psa_sign_hash() and psa_verify_hash().

This encompasses all strict hash-and-sign algorithms categorized by PSA_ALG_IS_HASH_AND_SIGN(), as well as algorithms that follow the paradigm more loosely:

Parameters

  • alg – An algorithm identifier (value of type psa_algorithm_t).

Returns

1 if alg is a signature algorithm that can be used to sign a hash. 0 if alg is a signature algorithm that can only be used to sign a message. 0 if alg is not a signature algorithm. This macro can return either 0 or 1 if alg is not a supported algorithm identifier.

PSA_ALG_IS_SIGN_MESSAGE(alg)

Whether the specified algorithm is a signature algorithm that can be used with psa_sign_message() and psa_verify_message().

Parameters
Returns

1 if alg is a signature algorithm that can be used to sign a message. 0 if alg is a signature algorithm that can only be used to sign an already-calculated hash. 0 if alg is not a signature algorithm. This macro can return either 0 or 1 if alg is not a supported algorithm identifier.

PSA_ALG_IS_HASH_AND_SIGN(alg)

Whether the specified algorithm is a hash-and-sign algorithm.

Hash-and-sign algorithms are asymmetric (public-key) signature algorithms structured in two parts: first the calculation of a hash in a way that does not depend on the key, then the calculation of a signature from the hash value and the key. Hash-and-sign algorithms encode the hash used for the hashing step, and you can call PSA_ALG_SIGN_GET_HASH to extract this algorithm.

Thus, for a hash-and-sign algorithm, psa_sign_message(key, alg, input, ...) is equivalent to 

psa_hash_compute(PSA_ALG_SIGN_GET_HASH(alg), input, ..., hash, ...);
psa_sign_hash(key, alg, hash, ..., signature, ...);

Most usefully, separating the hash from the signature allows the hash to be calculated in multiple steps with psa_hash_setup(), psa_hash_update() and psa_hash_finish(). Likewise psa_verify_message() is equivalent to calculating the hash and then calling psa_verify_hash().

Parameters
Returns

1 if alg is a hash-and-sign algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported algorithm identifier.

PSA_ALG_SIGN_GET_HASH(alg)

Get the hash used by a hash-and-sign signature algorithm.

A hash-and-sign algorithm is a signature algorithm which is composed of two phases: first a hashing phase which does not use the key and produces a hash of the input message, then a signing phase which only uses the hash and the key and not the message itself.

Parameters

  • alg – A signature algorithm (PSA_ALG_XXX value such that PSA_ALG_IS_SIGN(alg) is true).

Returns

The underlying hash algorithm if alg is a hash-and-sign algorithm.

Returns

0 if alg is a signature algorithm that does not follow the hash-and-sign structure.

Returns

Unspecified if alg is not a signature algorithm or if it is not supported by the implementation.

PSA_ALG_RSA_PKCS1V15_CRYPT

RSA PKCS#1 v1.5 encryption.

Warning

Calling psa_asymmetric_decrypt() with this algorithm as a parameter is considered an inherently dangerous function (CWE-242). Unless it is used in a side channel free and safe way (eg. implementing the TLS protocol as per 7.4.7.1 of RFC 5246), the calling code is vulnerable.

PSA_ALG_RSA_OAEP_BASE
PSA_ALG_RSA_OAEP(hash_alg)

RSA OAEP encryption.

This is the encryption scheme defined by RFC 8017 (PKCS#1: RSA Cryptography Specifications) under the name RSAES-OAEP, with the message generation function MGF1.

Parameters

  • hash_alg – The hash algorithm (PSA_ALG_XXX value such that PSA_ALG_IS_HASH(hash_alg) is true) to use for MGF1.

Returns

The corresponding RSA OAEP encryption algorithm.

Returns

Unspecified if hash_alg is not a supported hash algorithm.

PSA_ALG_IS_RSA_OAEP(alg)
PSA_ALG_RSA_OAEP_GET_HASH(alg)
PSA_ALG_HKDF_BASE
PSA_ALG_HKDF(hash_alg)

Macro to build an HKDF algorithm.

For example, PSA_ALG_HKDF(PSA_ALG_SHA_256) is HKDF using HMAC-SHA-256.

This key derivation algorithm uses the following inputs:

Warning

HKDF processes the salt as follows: first hash it with hash_alg if the salt is longer than the block size of the hash algorithm; then pad with null bytes up to the block size. As a result, it is possible for distinct salt inputs to result in the same outputs. To ensure unique outputs, it is recommended to use a fixed length for salt values.

Parameters

  • hash_alg – A hash algorithm (PSA_ALG_XXX value such that PSA_ALG_IS_HASH(hash_alg) is true).

Returns

The corresponding HKDF algorithm.

Returns

Unspecified if hash_alg is not a supported hash algorithm.

PSA_ALG_IS_HKDF(alg)

Whether the specified algorithm is an HKDF algorithm.

HKDF is a family of key derivation algorithms that are based on a hash function and the HMAC construction.

Parameters
Returns

1 if alg is an HKDF algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported key derivation algorithm identifier.

PSA_ALG_HKDF_GET_HASH(hkdf_alg)
PSA_ALG_HKDF_EXTRACT_BASE
PSA_ALG_HKDF_EXTRACT(hash_alg)

Macro to build an HKDF-Extract algorithm.

For example, PSA_ALG_HKDF_EXTRACT(PSA_ALG_SHA_256) is HKDF-Extract using HMAC-SHA-256.

This key derivation algorithm uses the following inputs:

  • PSA_KEY_DERIVATION_INPUT_SALT is the salt.

  • PSA_KEY_DERIVATION_INPUT_SECRET is the input keying material used in the “extract” step. The inputs are mandatory and must be passed in the order above. Each input may only be passed once.

Warning

HKDF-Extract is not meant to be used on its own. PSA_ALG_HKDF should be used instead if possible. PSA_ALG_HKDF_EXTRACT is provided as a separate algorithm for the sake of protocols that use it as a building block. It may also be a slight performance optimization in applications that use HKDF with the same salt and key but many different info strings.

Warning

HKDF processes the salt as follows: first hash it with hash_alg if the salt is longer than the block size of the hash algorithm; then pad with null bytes up to the block size. As a result, it is possible for distinct salt inputs to result in the same outputs. To ensure unique outputs, it is recommended to use a fixed length for salt values.

Parameters

  • hash_alg – A hash algorithm (PSA_ALG_XXX value such that PSA_ALG_IS_HASH(hash_alg) is true).

Returns

The corresponding HKDF-Extract algorithm.

Returns

Unspecified if hash_alg is not a supported hash algorithm.

PSA_ALG_IS_HKDF_EXTRACT(alg)

Whether the specified algorithm is an HKDF-Extract algorithm.

HKDF-Extract is a family of key derivation algorithms that are based on a hash function and the HMAC construction.

Parameters
Returns

1 if alg is an HKDF-Extract algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported key derivation algorithm identifier.

PSA_ALG_HKDF_EXPAND_BASE
PSA_ALG_HKDF_EXPAND(hash_alg)

Macro to build an HKDF-Expand algorithm.

For example, PSA_ALG_HKDF_EXPAND(PSA_ALG_SHA_256) is HKDF-Expand using HMAC-SHA-256.

This key derivation algorithm uses the following inputs:

  • PSA_KEY_DERIVATION_INPUT_SECRET is the pseudorandom key (PRK).

  • PSA_KEY_DERIVATION_INPUT_INFO is the info string.

The inputs are mandatory and must be passed in the order above. Each input may only be passed once.

Warning

HKDF-Expand is not meant to be used on its own. PSA_ALG_HKDF should be used instead if possible. PSA_ALG_HKDF_EXPAND is provided as a separate algorithm for the sake of protocols that use it as a building block. It may also be a slight performance optimization in applications that use HKDF with the same salt and key but many different info strings.

Parameters

  • hash_alg – A hash algorithm (PSA_ALG_XXX value such that PSA_ALG_IS_HASH(hash_alg) is true).

Returns

The corresponding HKDF-Expand algorithm.

Returns

Unspecified if hash_alg is not a supported hash algorithm.

PSA_ALG_IS_HKDF_EXPAND(alg)

Whether the specified algorithm is an HKDF-Expand algorithm.

HKDF-Expand is a family of key derivation algorithms that are based on a hash function and the HMAC construction.

Parameters
Returns

1 if alg is an HKDF-Expand algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported key derivation algorithm identifier.

PSA_ALG_IS_ANY_HKDF(alg)

Whether the specified algorithm is an HKDF or HKDF-Extract or HKDF-Expand algorithm.

Parameters
Returns

1 if alg is any HKDF type algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported key derivation algorithm identifier.

PSA_ALG_TLS12_PRF_BASE
PSA_ALG_TLS12_PRF(hash_alg)

Macro to build a TLS-1.2 PRF algorithm.

TLS 1.2 uses a custom pseudorandom function (PRF) for key schedule, specified in Section 5 of RFC 5246. It is based on HMAC and can be used with either SHA-256 or SHA-384.

This key derivation algorithm uses the following inputs, which must be passed in the order given here:

For the application to TLS-1.2 key expansion, the seed is the concatenation of ServerHello.Random + ClientHello.Random, and the label is “key expansion”.

For example, PSA_ALG_TLS12_PRF(PSA_ALG_SHA_256) represents the TLS 1.2 PRF using HMAC-SHA-256.

Parameters

  • hash_alg – A hash algorithm (PSA_ALG_XXX value such that PSA_ALG_IS_HASH(hash_alg) is true).

Returns

The corresponding TLS-1.2 PRF algorithm.

Returns

Unspecified if hash_alg is not a supported hash algorithm.

PSA_ALG_IS_TLS12_PRF(alg)

Whether the specified algorithm is a TLS-1.2 PRF algorithm.

Parameters
Returns

1 if alg is a TLS-1.2 PRF algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported key derivation algorithm identifier.

PSA_ALG_TLS12_PRF_GET_HASH(hkdf_alg)
PSA_ALG_TLS12_PSK_TO_MS_BASE
PSA_ALG_TLS12_PSK_TO_MS(hash_alg)

Macro to build a TLS-1.2 PSK-to-MasterSecret algorithm.

In a pure-PSK handshake in TLS 1.2, the master secret is derived from the PreSharedKey (PSK) through the application of padding (RFC 4279, Section 2) and the TLS-1.2 PRF (RFC 5246, Section 5). The latter is based on HMAC and can be used with either SHA-256 or SHA-384.

This key derivation algorithm uses the following inputs, which must be passed in the order given here:

For the application to TLS-1.2, the seed (which is forwarded to the TLS-1.2 PRF) is the concatenation of the ClientHello.Random + ServerHello.Random, the label is “master secret” or “extended master secret” and the other secret depends on the key exchange specified in the cipher suite:

For example, PSA_ALG_TLS12_PSK_TO_MS(PSA_ALG_SHA_256) represents the TLS-1.2 PSK to MasterSecret derivation PRF using HMAC-SHA-256.

Parameters

  • hash_alg – A hash algorithm (PSA_ALG_XXX value such that PSA_ALG_IS_HASH(hash_alg) is true).

Returns

The corresponding TLS-1.2 PSK to MS algorithm.

Returns

Unspecified if hash_alg is not a supported hash algorithm.

PSA_ALG_IS_TLS12_PSK_TO_MS(alg)

Whether the specified algorithm is a TLS-1.2 PSK to MS algorithm.

Parameters
Returns

1 if alg is a TLS-1.2 PSK to MS algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported key derivation algorithm identifier.

PSA_ALG_TLS12_PSK_TO_MS_GET_HASH(hkdf_alg)
PSA_ALG_TLS12_ECJPAKE_TO_PMS
PSA_ALG_KEY_DERIVATION_STRETCHING_FLAG
PSA_ALG_PBKDF2_HMAC_BASE
PSA_ALG_PBKDF2_HMAC(hash_alg)

Macro to build a PBKDF2-HMAC password hashing / key stretching algorithm.

PBKDF2 is defined by PKCS#5, republished as RFC 8018 (section 5.2). This macro specifies the PBKDF2 algorithm constructed using a PRF based on HMAC with the specified hash. For example, PSA_ALG_PBKDF2_HMAC(PSA_ALG_SHA_256) specifies PBKDF2 using the PRF HMAC-SHA-256.

This key derivation algorithm uses the following inputs, which must be provided in the following order:

  • PSA_KEY_DERIVATION_INPUT_COST is the iteration count. This input step must be used exactly once.

  • PSA_KEY_DERIVATION_INPUT_SALT is the salt. This input step must be used one or more times; if used several times, the inputs will be concatenated. This can be used to build the final salt from multiple sources, both public and secret (also known as pepper).

  • PSA_KEY_DERIVATION_INPUT_PASSWORD is the password to be hashed. This input step must be used exactly once.

Parameters

  • hash_alg – A hash algorithm (PSA_ALG_XXX value such that PSA_ALG_IS_HASH(hash_alg) is true).

Returns

The corresponding PBKDF2-HMAC-XXX algorithm.

Returns

Unspecified if hash_alg is not a supported hash algorithm.

PSA_ALG_IS_PBKDF2_HMAC(alg)

Whether the specified algorithm is a PBKDF2-HMAC algorithm.

Parameters
Returns

1 if alg is a PBKDF2-HMAC algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported key derivation algorithm identifier.

PSA_ALG_PBKDF2_HMAC_GET_HASH(pbkdf2_alg)
PSA_ALG_PBKDF2_AES_CMAC_PRF_128

The PBKDF2-AES-CMAC-PRF-128 password hashing / key stretching algorithm.

PBKDF2 is defined by PKCS#5, republished as RFC 8018 (section 5.2). This macro specifies the PBKDF2 algorithm constructed using the AES-CMAC-PRF-128 PRF specified by RFC 4615.

This key derivation algorithm uses the same inputs as PSA_ALG_PBKDF2_HMAC() with the same constraints.

PSA_ALG_IS_PBKDF2(kdf_alg)
PSA_ALG_KEY_DERIVATION_MASK
PSA_ALG_KEY_AGREEMENT_MASK
PSA_ALG_KEY_AGREEMENT(ka_alg, kdf_alg)

Macro to build a combined algorithm that chains a key agreement with a key derivation.

Parameters
Returns

The corresponding key agreement and derivation algorithm.

Returns

Unspecified if ka_alg is not a supported key agreement algorithm or kdf_alg is not a supported key derivation algorithm.

PSA_ALG_KEY_AGREEMENT_GET_KDF(alg)
PSA_ALG_KEY_AGREEMENT_GET_BASE(alg)
PSA_ALG_IS_RAW_KEY_AGREEMENT(alg)

Whether the specified algorithm is a raw key agreement algorithm.

A raw key agreement algorithm is one that does not specify a key derivation function. Usually, raw key agreement algorithms are constructed directly with a PSA_ALG_xxx macro while non-raw key agreement algorithms are constructed with PSA_ALG_KEY_AGREEMENT().

Parameters
Returns

1 if alg is a raw key agreement algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported algorithm identifier.

PSA_ALG_IS_KEY_DERIVATION_OR_AGREEMENT(alg)
PSA_ALG_FFDH

The finite-field Diffie-Hellman (DH) key agreement algorithm.

The shared secret produced by key agreement is g^{ab} in big-endian format. It is ceiling(m / 8) bytes long where m is the size of the prime p in bits.

PSA_ALG_IS_FFDH(alg)

Whether the specified algorithm is a finite field Diffie-Hellman algorithm.

This includes the raw finite field Diffie-Hellman algorithm as well as finite-field Diffie-Hellman followed by any supporter key derivation algorithm.

Parameters
Returns

1 if alg is a finite field Diffie-Hellman algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported key agreement algorithm identifier.

PSA_ALG_ECDH

The elliptic curve Diffie-Hellman (ECDH) key agreement algorithm.

The shared secret produced by key agreement is the x-coordinate of the shared secret point. It is always ceiling(m / 8) bytes long where m is the bit size associated with the curve, i.e. the bit size of the order of the curve’s coordinate field. When m is not a multiple of 8, the byte containing the most significant bit of the shared secret is padded with zero bits. The byte order is either little-endian or big-endian depending on the curve type.

  • For Montgomery curves (curve types PSA_ECC_FAMILY_CURVEXXX), the shared secret is the x-coordinate of d_A Q_B = d_B Q_A in little-endian byte order. The bit size is 448 for Curve448 and 255 for Curve25519.

  • For Weierstrass curves over prime fields (curve types PSA_ECC_FAMILY_SECPXXX and PSA_ECC_FAMILY_BRAINPOOL_PXXX), the shared secret is the x-coordinate of d_A Q_B = d_B Q_A in big-endian byte order. The bit size is m = ceiling(log_2(p)) for the field F_p.

  • For Weierstrass curves over binary fields (curve types PSA_ECC_FAMILY_SECTXXX), the shared secret is the x-coordinate of d_A Q_B = d_B Q_A in big-endian byte order. The bit size is m for the field F_{2^m}.

PSA_ALG_IS_ECDH(alg)

Whether the specified algorithm is an elliptic curve Diffie-Hellman algorithm.

This includes the raw elliptic curve Diffie-Hellman algorithm as well as elliptic curve Diffie-Hellman followed by any supporter key derivation algorithm.

Parameters
Returns

1 if alg is an elliptic curve Diffie-Hellman algorithm, 0 otherwise. This macro may return either 0 or 1 if alg is not a supported key agreement algorithm identifier.

PSA_ALG_IS_WILDCARD(alg)

Whether the specified algorithm encoding is a wildcard.

Wildcard values may only be used to set the usage algorithm field in a policy, not to perform an operation.

Parameters
Returns

1 if alg is a wildcard algorithm encoding.

Returns

0 if alg is a non-wildcard algorithm encoding (suitable for an operation).

Returns

This macro may return either 0 or 1 if alg is not a supported algorithm identifier.

PSA_ALG_GET_HASH(alg)

Get the hash used by a composite algorithm.

Parameters
Returns

The underlying hash algorithm if alg is a composite algorithm that uses a hash algorithm.

Returns

0 if alg is not a composite algorithm that uses a hash.

Typedefs

typedef uint16_t psa_key_type_t

Encoding of a key type.

Values of this type are generally constructed by macros called PSA_KEY_TYPE_xxx.

Note

Values of this type are encoded in the persistent key store. Any changes to existing values will require bumping the storage format version and providing a translation when reading the old format.

typedef uint8_t psa_ecc_family_t

The type of PSA elliptic curve family identifiers.

Values of this type are generally constructed by macros called PSA_ECC_FAMILY_xxx.

The curve identifier is required to create an ECC key using the PSA_KEY_TYPE_ECC_KEY_PAIR() or PSA_KEY_TYPE_ECC_PUBLIC_KEY() macros.

Values defined by this standard will never be in the range 0x80-0xff. Vendors who define additional families must use an encoding in this range.

Note

Values of this type are encoded in the persistent key store. Any changes to existing values will require bumping the storage format version and providing a translation when reading the old format.

typedef uint8_t psa_dh_family_t

The type of PSA Diffie-Hellman group family identifiers.

Values of this type are generally constructed by macros called PSA_DH_FAMILY_xxx.

The group identifier is required to create a Diffie-Hellman key using the PSA_KEY_TYPE_DH_KEY_PAIR() or PSA_KEY_TYPE_DH_PUBLIC_KEY() macros.

Values defined by this standard will never be in the range 0x80-0xff. Vendors who define additional families must use an encoding in this range.

Note

Values of this type are encoded in the persistent key store. Any changes to existing values will require bumping the storage format version and providing a translation when reading the old format.

typedef uint32_t psa_algorithm_t

Encoding of a cryptographic algorithm.

Values of this type are generally constructed by macros called PSA_ALG_xxx.

For algorithms that can be applied to multiple key types, this type does not encode the key type. For example, for symmetric ciphers based on a block cipher, psa_algorithm_t encodes the block cipher mode and the padding mode while the block cipher itself is encoded via psa_key_type_t.

Note

Values of this type are encoded in the persistent key store. Any changes to existing values will require bumping the storage format version and providing a translation when reading the old format.