10.7. Asymmetric signature

10.7.1. Asymmetric signature algorithms

`PSA_ALG_RSA_PKCS1V15_SIGN` (macro)

The RSA PKCS#1 v1.5 message signature scheme, with hashing.

#define PSA_ALG_RSA_PKCS1V15_SIGN(hash_alg) /* specification-defined value */

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 key policy.

Returns

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

Unspecified if hash_alg is not a supported hash algorithm.

Description

This algorithm can be used with both the message and hash signature functions.

This signature scheme is defined by PKCS #1: RSA Cryptography Specifications Version 2.2 [RFC8017] §8.2 under the name RSASSA-PKCS1-v1_5.

When used with psa_sign_hash() or psa_verify_hash(), the provided hash parameter is used as H from step 2 onwards in the message encoding algorithm EMSA-PKCS1-V1_5-ENCODE() in [RFC8017] §9.2. H is usually the message digest, using the hash_alg hash algorithm.

`PSA_ALG_RSA_PKCS1V15_SIGN_RAW` (macro)

The raw RSA PKCS#1 v1.5 signature algorithm, without hashing.

#define PSA_ALG_RSA_PKCS1V15_SIGN_RAW ((psa_algorithm_t) 0x06000200)

This algorithm can be only used with the psa_sign_hash() and psa_verify_hash() functions.

This signature scheme is defined by PKCS #1: RSA Cryptography Specifications Version 2.2 [RFC8017] §8.2 under the name RSASSA-PKCS1-v1_5.

The hash parameter to psa_sign_hash() or psa_verify_hash() is used as T from step 3 onwards in the message encoding algorithm EMSA-PKCS1-V1_5-ENCODE() in [RFC8017] §9.2. T is the DER encoding of the DigestInfo structure normally produced by step 2 in the message encoding algorithm.

`PSA_ALG_RSA_PSS` (macro)

The RSA PSS message signature scheme, with hashing.

#define PSA_ALG_RSA_PSS(hash_alg) /* specification-defined value */

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 key policy.

Returns

The corresponding RSA PSS signature algorithm.

Unspecified if hash_alg is not a supported hash algorithm.

Description

This algorithm can be used with both the message and hash signature functions.

This algorithm is randomized: each invocation returns a different, equally valid signature.

This is the signature scheme defined by [RFC8017] §8.1 under the name RSASSA-PSS, with the following options:

The mask generation function is MGF1 defined by [RFC8017] Appendix B.
The salt length is equal to the length of the hash.
The specified hash algorithm is used to hash the input message, to create the salted hash, and for the mask generation.

`PSA_ALG_ECDSA` (macro)

The randomized ECDSA signature scheme, with hashing.

#define PSA_ALG_ECDSA(hash_alg) /* specification-defined value */

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 key policy.

Returns

The corresponding randomized ECDSA signature algorithm.

Unspecified if hash_alg is not a supported hash algorithm.

Description

This algorithm can be used with both the message and hash signature functions.

This algorithm is randomized: each invocation returns a different, equally valid signature.

Note

When based on the same hash algorithm, the verification operations for PSA_ALG_ECDSA and PSA_ALG_DETERMINISTIC_ECDSA are identical. A signature created using PSA_ALG_ECDSA can be verified with the same key using either PSA_ALG_ECDSA or PSA_ALG_DETERMINISTIC_ECDSA. Similarly, a signature created using PSA_ALG_DETERMINISTIC_ECDSA can be verified with the same key using either PSA_ALG_ECDSA or PSA_ALG_DETERMINISTIC_ECDSA.

In particular, it is impossible to determine whether a signature was produced with deterministic ECDSA or with randomized ECDSA: it is only possible to verify that a signature was made with ECDSA with the private key corresponding to the public key used for the verification.

This signature scheme is defined by SEC 1: Elliptic Curve Cryptography [SEC1], and also by Public Key Cryptography For The Financial Services Industry: The Elliptic Curve Digital Signature Algorithm (ECDSA) [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, with the most significant octet first.

`PSA_ALG_ECDSA_ANY` (macro)

The randomized ECDSA signature scheme, without hashing.

#define PSA_ALG_ECDSA_ANY ((psa_algorithm_t) 0x06000600)

This algorithm can be only used with the psa_sign_hash() and psa_verify_hash() functions.

This algorithm is randomized: each invocation returns a different, equally valid signature.

This is the same signature scheme as PSA_ALG_ECDSA(), but without specifying a hash algorithm, and skipping the message hashing operation.

This algorithm is only recommended to sign or verify a sequence of bytes that are an already-calculated hash. Note that the input is padded with zeros on the left or truncated on the right as required to fit the curve size.

`PSA_ALG_DETERMINISTIC_ECDSA` (macro)

Deterministic ECDSA signature scheme, with hashing.

#define PSA_ALG_DETERMINISTIC_ECDSA(hash_alg) /* specification-defined value */

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 key policy.

Returns

The corresponding deterministic ECDSA signature algorithm.

Unspecified if hash_alg is not a supported hash algorithm.

Description

This algorithm can be used with both the message and hash signature functions.

Note

When based on the same hash algorithm, the verification operations for PSA_ALG_ECDSA and PSA_ALG_DETERMINISTIC_ECDSA are identical. A signature created using PSA_ALG_ECDSA can be verified with the same key using either PSA_ALG_ECDSA or PSA_ALG_DETERMINISTIC_ECDSA. Similarly, a signature created using PSA_ALG_DETERMINISTIC_ECDSA can be verified with the same key using either PSA_ALG_ECDSA or PSA_ALG_DETERMINISTIC_ECDSA.

In particular, it is impossible to determine whether a signature was produced with deterministic ECDSA or with randomized ECDSA: it is only possible to verify that a signature was made with ECDSA with the private key corresponding to the public key used for the verification.

This is the deterministic ECDSA signature scheme defined by Deterministic Usage of the Digital Signature Algorithm (DSA) and Elliptic Curve Digital Signature Algorithm (ECDSA) [RFC6979].

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

10.7.2. Asymmetric signature functions

`psa_sign_message` (function)

Sign a message with a private key. For hash-and-sign algorithms, this includes the hashing step.

psa_status_t psa_sign_message(psa_key_id_t key,
                              psa_algorithm_t alg,
                              const uint8_t * input,
                              size_t input_length,
                              uint8_t * signature,
                              size_t signature_size,
                              size_t * signature_length);

Parameters

key

Identifier of the key to use for the operation. It must be an asymmetric key pair. The key must allow the usage PSA_KEY_USAGE_SIGN_MESSAGE.

alg

An asymmetric signature algorithm (PSA_ALG_XXX value such that PSA_ALG_IS_SIGN_MESSAGE(alg) is true), that is compatible with the type of key.

input

The input message to sign.

input_length

Size of the input buffer in bytes.

signature

Buffer where the signature is to be written.

signature_size

Size of the signature buffer in bytes. This must be appropriate for the selected algorithm and key:

The required signature size is PSA_SIGN_OUTPUT_SIZE(key_type, key_bits, alg) where key_type and key_bits are the type and bit-size respectively of key.
PSA_SIGNATURE_MAX_SIZE evaluates to the maximum signature size of any supported signature algorithm.

signature_length

On success, the number of bytes that make up the returned signature value.

Returns: psa_status_t

PSA_SUCCESS
PSA_ERROR_INVALID_HANDLE
PSA_ERROR_NOT_PERMITTED: The key does not have the PSA_KEY_USAGE_SIGN_MESSAGE flag, or it does not permit the requested algorithm.
PSA_ERROR_BUFFER_TOO_SMALL: The size of the signature buffer is too small. PSA_SIGN_OUTPUT_SIZE() or PSA_SIGNATURE_MAX_SIZE can be used to determine the required buffer size.
PSA_ERROR_NOT_SUPPORTED
PSA_ERROR_INVALID_ARGUMENT
PSA_ERROR_INSUFFICIENT_MEMORY
PSA_ERROR_COMMUNICATION_FAILURE
PSA_ERROR_HARDWARE_FAILURE
PSA_ERROR_CORRUPTION_DETECTED
PSA_ERROR_STORAGE_FAILURE
PSA_ERROR_DATA_CORRUPT
PSA_ERROR_DATA_INVALID
PSA_ERROR_INSUFFICIENT_ENTROPY
PSA_ERROR_BAD_STATE: The library has not been previously initialized by psa_crypto_init(). It is implementation-dependent whether a failure to initialize results in this error code.

Description

Note

To perform a multi-part hash-and-sign signature algorithm, first use a multi-part hash operation and then pass the resulting hash to psa_sign_hash(). PSA_ALG_GET_HASH(alg) can be used to determine the hash algorithm to use.

`psa_verify_message` (function)

Verify the signature of a message with a public key, using a hash-and-sign verification algorithm.

psa_status_t psa_verify_message(psa_key_id_t key,
                                psa_algorithm_t alg,
                                const uint8_t * input,
                                size_t input_length,
                                const uint8_t * signature,
                                size_t signature_length);

Parameters

key: Identifier of the key to use for the operation. It must be a public key or an asymmetric key pair. The key must allow the usage PSA_KEY_USAGE_VERIFY_MESSAGE.
alg: An asymmetric signature algorithm (PSA_ALG_XXX value such that PSA_ALG_IS_SIGN_MESSAGE(alg) is true), that is compatible with the type of key.
input: The message whose signature is to be verified.
input_length: Size of the input buffer in bytes.
signature: Buffer containing the signature to verify.
signature_length: Size of the signature buffer in bytes.

Returns: psa_status_t

PSA_SUCCESS: The signature is valid.
PSA_ERROR_INVALID_HANDLE
PSA_ERROR_NOT_PERMITTED: The key does not have the PSA_KEY_USAGE_VERIFY_MESSAGE flag, or it does not permit the requested algorithm.
PSA_ERROR_INVALID_SIGNATURE: The calculation was performed successfully, but the passed signature is not a valid signature.
PSA_ERROR_NOT_SUPPORTED
PSA_ERROR_INVALID_ARGUMENT
PSA_ERROR_INSUFFICIENT_MEMORY
PSA_ERROR_COMMUNICATION_FAILURE
PSA_ERROR_HARDWARE_FAILURE
PSA_ERROR_CORRUPTION_DETECTED
PSA_ERROR_STORAGE_FAILURE
PSA_ERROR_DATA_CORRUPT
PSA_ERROR_DATA_INVALID
PSA_ERROR_BAD_STATE: The library has not been previously initialized by psa_crypto_init(). It is implementation-dependent whether a failure to initialize results in this error code.

Description

Note

To perform a multi-part hash-and-sign signature verification algorithm, first use a multi-part hash operation to hash the message and then pass the resulting hash to psa_verify_hash(). PSA_ALG_GET_HASH(alg) can be used to determine the hash algorithm to use.

`psa_sign_hash` (function)

Sign an already-calculated hash with a private key.

psa_status_t psa_sign_hash(psa_key_id_t key,
                           psa_algorithm_t alg,
                           const uint8_t * hash,
                           size_t hash_length,
                           uint8_t * signature,
                           size_t signature_size,
                           size_t * signature_length);

Parameters

key

Identifier of the key to use for the operation. It must be an asymmetric key pair. The key must allow the usage PSA_KEY_USAGE_SIGN_HASH.

alg

An asymmetric signature algorithm that separates the hash and sign operations (PSA_ALG_XXX value such that PSA_ALG_IS_SIGN_HASH(alg) is true), that is compatible with the type of key.

hash

The input to sign. This is usually the hash of a message. See the detailed description of this function and the description of individual signature algorithms for a detailed description of acceptable inputs.

hash_length

Size of the hash buffer in bytes.

signature

Buffer where the signature is to be written.

signature_size

Size of the signature buffer in bytes. This must be appropriate for the selected algorithm and key:

The required signature size is PSA_SIGN_OUTPUT_SIZE(key_type, key_bits, alg) where key_type and key_bits are the type and bit-size respectively of key.
PSA_SIGNATURE_MAX_SIZE evaluates to the maximum signature size of any supported signature algorithm.

signature_length

On success, the number of bytes that make up the returned signature value.

Returns: psa_status_t

PSA_SUCCESS
PSA_ERROR_INVALID_HANDLE
PSA_ERROR_NOT_PERMITTED: The key does not have the PSA_KEY_USAGE_SIGN_HASH flag, or it does not permit the requested algorithm.
PSA_ERROR_BUFFER_TOO_SMALL: The size of the signature buffer is too small. PSA_SIGN_OUTPUT_SIZE() or PSA_SIGNATURE_MAX_SIZE can be used to determine the required buffer size.
PSA_ERROR_NOT_SUPPORTED
PSA_ERROR_INVALID_ARGUMENT
PSA_ERROR_INSUFFICIENT_MEMORY
PSA_ERROR_COMMUNICATION_FAILURE
PSA_ERROR_HARDWARE_FAILURE
PSA_ERROR_CORRUPTION_DETECTED
PSA_ERROR_STORAGE_FAILURE
PSA_ERROR_DATA_CORRUPT
PSA_ERROR_DATA_INVALID
PSA_ERROR_INSUFFICIENT_ENTROPY
PSA_ERROR_BAD_STATE: The library has not been previously initialized by psa_crypto_init(). It is implementation-dependent whether a failure to initialize results in this error code.

Description

With most signature mechanisms that follow the hash-and-sign paradigm, the hash input to this function is the hash of the message to sign. The hash algorithm is encoded in the signature algorithm.

Some hash-and-sign mechanisms apply a padding or encoding to the hash. In such cases, the encoded hash must be passed to this function. The current version of this specification defines one such signature algorithm: PSA_ALG_RSA_PKCS1V15_SIGN_RAW.

Note

To perform a hash-and-sign algorithm, the hash must be calculated before passing it to this function. This can be done by calling psa_hash_compute() or with a multi-part hash operation. Alternatively, to hash and sign a message in a single call, use psa_sign_message().

`psa_verify_hash` (function)

Verify the signature of a hash or short message using a public key.

psa_status_t psa_verify_hash(psa_key_id_t key,
                             psa_algorithm_t alg,
                             const uint8_t * hash,
                             size_t hash_length,
                             const uint8_t * signature,
                             size_t signature_length);

Parameters

key: Identifier of the key to use for the operation. It must be a public key or an asymmetric key pair. The key must allow the usage PSA_KEY_USAGE_VERIFY_HASH.
alg: An asymmetric signature algorithm that separates the hash and sign operations (PSA_ALG_XXX value such that PSA_ALG_IS_SIGN_HASH(alg) is true), that is compatible with the type of key.
hash: The input whose signature is to be verified. This is usually the hash of a message. See the detailed description of this function and the description of individual signature algorithms for a detailed description of acceptable inputs.
hash_length: Size of the hash buffer in bytes.
signature: Buffer containing the signature to verify.
signature_length: Size of the signature buffer in bytes.

Returns: psa_status_t

PSA_SUCCESS: The signature is valid.
PSA_ERROR_INVALID_HANDLE
PSA_ERROR_NOT_PERMITTED: The key does not have the PSA_KEY_USAGE_VERIFY_HASH flag, or it does not permit the requested algorithm.
PSA_ERROR_INVALID_SIGNATURE: The calculation was performed successfully, but the passed signature is not a valid signature.
PSA_ERROR_NOT_SUPPORTED
PSA_ERROR_INVALID_ARGUMENT
PSA_ERROR_INSUFFICIENT_MEMORY
PSA_ERROR_COMMUNICATION_FAILURE
PSA_ERROR_HARDWARE_FAILURE
PSA_ERROR_CORRUPTION_DETECTED
PSA_ERROR_STORAGE_FAILURE
PSA_ERROR_DATA_CORRUPT
PSA_ERROR_DATA_INVALID
PSA_ERROR_BAD_STATE: The library has not been previously initialized by psa_crypto_init(). It is implementation-dependent whether a failure to initialize results in this error code.

Description

With most signature mechanisms that follow the hash-and-sign paradigm, the hash input to this function is the hash of the message to sign. The hash algorithm is encoded in the signature algorithm.

Some hash-and-sign mechanisms apply a padding or encoding to the hash. In such cases, the encoded hash must be passed to this function. The current version of this specification defines one such signature algorithm: PSA_ALG_RSA_PKCS1V15_SIGN_RAW.

Note

To perform a hash-and-sign verification algorithm, the hash must be calculated before passing it to this function. This can be done by calling psa_hash_compute() or with a multi-part hash operation. Alternatively, to hash and verify a message signature in a single call, use psa_verify_message().

10.7.3. Support macros

`PSA_ALG_IS_SIGN_MESSAGE` (macro)

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

#define PSA_ALG_IS_SIGN_MESSAGE(alg) /* specification-defined value */

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 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_SIGN_HASH` (macro)

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

#define PSA_ALG_IS_SIGN_HASH(alg) /* specification-defined value */

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_RSA_PKCS1V15_SIGN` (macro)

Whether the specified algorithm is an RSA PKCS#1 v1.5 signature algorithm.

#define PSA_ALG_IS_RSA_PKCS1V15_SIGN(alg) /* specification-defined value */

Parameters

alg: An algorithm identifier (value of type psa_algorithm_t).

Returns

1 if alg is an RSA PKCS#1 v1.5 signature algorithm, 0 otherwise.

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

`PSA_ALG_IS_RSA_PSS` (macro)

Whether the specified algorithm is an RSA PSS signature algorithm.

#define PSA_ALG_IS_RSA_PSS(alg) /* specification-defined value */

Parameters

alg: An algorithm identifier (value of type psa_algorithm_t).

Returns

1 if alg is an RSA PSS signature algorithm, 0 otherwise.

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

`PSA_ALG_IS_ECDSA` (macro)

Whether the specified algorithm is ECDSA.

#define PSA_ALG_IS_ECDSA(alg) /* specification-defined value */

Parameters

alg: An algorithm identifier (value of type psa_algorithm_t).

Returns

1 if alg is an ECDSA algorithm, 0 otherwise.

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

`PSA_ALG_IS_DETERMINISTIC_ECDSA` (macro)

Whether the specified algorithm is deterministic ECDSA.

#define PSA_ALG_IS_DETERMINISTIC_ECDSA(alg) /* specification-defined value */

Parameters

alg: An algorithm identifier (value of type psa_algorithm_t).

Returns

1 if alg is a deterministic ECDSA algorithm, 0 otherwise.

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

Description

`PSA_ALG_IS_RANDOMIZED_ECDSA` (macro)

Whether the specified algorithm is randomized ECDSA.

#define PSA_ALG_IS_RANDOMIZED_ECDSA(alg) /* specification-defined value */

Parameters

alg: An algorithm identifier (value of type psa_algorithm_t).

Returns

1 if alg is a randomized ECDSA algorithm, 0 otherwise.

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

Description

`PSA_ALG_IS_HASH_AND_SIGN` (macro)

Whether the specified algorithm is a hash-and-sign algorithm that signs exactly the hash value.

#define PSA_ALG_IS_HASH_AND_SIGN(alg) /* specification-defined value */

Parameters

alg: An algorithm identifier (value of type psa_algorithm_t).

Returns

1 if alg is a hash-and-sign algorithm that signs exactly the hash value, 0 otherwise. This macro can return either 0 or 1 if alg is not a supported algorithm identifier.

Description

This macro identifies algorithms that can be used with psa_sign_hash() that use the exact message hash value as an input the signature operation. This excludes hash-and-sign algorithms that require a encoded or modified hash for the signature step in the algorithm, such as PSA_ALG_RSA_PKCS1V15_SIGN_RAW.

`PSA_ALG_ANY_HASH` (macro)

When setting a hash-and-sign algorithm in a key policy, permit any hash algorithm.

#define PSA_ALG_ANY_HASH ((psa_algorithm_t)0x020000ff)

This value can be used to form the permitted algorithm attribute of a key policy for a signature algorithm that is parametrized by a hash. A key with this policy can then be used to perform operations using the same signature algorithm parametrized with any supported hash. A signature algorithm created using this macro is a wildcard algorithm, and PSA_ALG_IS_WILDCARD() will return true.

This value must 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 must not be used to build an algorithm specification to perform an operation. It is only valid for setting the permitted algorithm in a key policy.

Usage

For example, suppose that PSA_xxx_SIGNATURE is one of the following macros:

PSA_ALG_RSA_PKCS1V15_SIGN
PSA_ALG_RSA_PSS
PSA_ALG_ECDSA
PSA_ALG_DETERMINISTIC_ECDSA

The following sequence of operations shows how PSA_ALG_ANY_HASH can be used in a key policy:

Set the key usage flags using PSA_ALG_ANY_HASH, for example:

psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_SIGN_MESSAGE); // or VERIFY_MESSAGE
psa_set_key_algorithm(&attributes, PSA_xxx_SIGNATURE(PSA_ALG_ANY_HASH));

Import or generate key material.

Call psa_sign_message() or psa_verify_message(), passing an algorithm built from PSA_xxx_SIGNATURE and a specific hash. Each call to sign or verify a message can use a different hash algorithm.

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

`PSA_SIGN_OUTPUT_SIZE` (macro)

Sufficient signature buffer size for psa_sign_message() and psa_sign_hash().

#define PSA_SIGN_OUTPUT_SIZE(key_type, key_bits, alg) \
    /* implementation-defined value */

Parameters

key_type: An asymmetric key type. This can be a key pair type or a public key type.
key_bits: The size of the key in bits.
alg: The signature algorithm.

Returns

If the parameters are valid and supported, return a buffer size in bytes that guarantees that psa_sign_message() and psa_sign_hash() will not fail with PSA_ERROR_BUFFER_TOO_SMALL. If the parameters are a valid combination that is not supported by the implementation, this macro must return either a sensible size or 0. If the parameters are not valid, the return value is unspecified.

Description

This macro returns a sufficient buffer size for a signature using a key of the specified type and size, with the specified algorithm. Note that the actual size of the signature might be smaller, as some algorithms produce a variable-size signature.

Warning

This function might evaluate its arguments multiple times or zero times. Providing arguments that have side effects will result in implementation-specific behavior, and is non-portable.

`PSA_SIGNATURE_MAX_SIZE` (macro)

Maximum size of an asymmetric signature.

#define PSA_SIGNATURE_MAX_SIZE /* implementation-defined value */

This macro must expand to a compile-time constant integer. It is recommended that this value is the maximum size of an asymmetric signature supported by the implementation, in bytes. The value must not be smaller than this maximum.

10.7. Asymmetric signature

10.7.1. Asymmetric signature algorithms

PSA_ALG_RSA_PKCS1V15_SIGN (macro)

PSA_ALG_RSA_PKCS1V15_SIGN_RAW (macro)

PSA_ALG_RSA_PSS (macro)

PSA_ALG_ECDSA (macro)

PSA_ALG_ECDSA_ANY (macro)

PSA_ALG_DETERMINISTIC_ECDSA (macro)

10.7.2. Asymmetric signature functions

psa_sign_message (function)

psa_verify_message (function)

psa_sign_hash (function)

psa_verify_hash (function)

10.7.3. Support macros

PSA_ALG_IS_SIGN_MESSAGE (macro)

PSA_ALG_IS_SIGN_HASH (macro)

PSA_ALG_IS_RSA_PKCS1V15_SIGN (macro)

PSA_ALG_IS_RSA_PSS (macro)

PSA_ALG_IS_ECDSA (macro)

PSA_ALG_IS_DETERMINISTIC_ECDSA (macro)

PSA_ALG_IS_RANDOMIZED_ECDSA (macro)

PSA_ALG_IS_HASH_AND_SIGN (macro)

PSA_ALG_ANY_HASH (macro)

PSA_SIGN_OUTPUT_SIZE (macro)

PSA_SIGNATURE_MAX_SIZE (macro)

`PSA_ALG_RSA_PKCS1V15_SIGN` (macro)

`PSA_ALG_RSA_PKCS1V15_SIGN_RAW` (macro)

`PSA_ALG_RSA_PSS` (macro)

`PSA_ALG_ECDSA` (macro)

`PSA_ALG_ECDSA_ANY` (macro)

`PSA_ALG_DETERMINISTIC_ECDSA` (macro)

`psa_sign_message` (function)

`psa_verify_message` (function)

`psa_sign_hash` (function)

`psa_verify_hash` (function)

`PSA_ALG_IS_SIGN_MESSAGE` (macro)

`PSA_ALG_IS_SIGN_HASH` (macro)

`PSA_ALG_IS_RSA_PKCS1V15_SIGN` (macro)

`PSA_ALG_IS_RSA_PSS` (macro)

`PSA_ALG_IS_ECDSA` (macro)

`PSA_ALG_IS_DETERMINISTIC_ECDSA` (macro)

`PSA_ALG_IS_RANDOMIZED_ECDSA` (macro)

`PSA_ALG_IS_HASH_AND_SIGN` (macro)

`PSA_ALG_ANY_HASH` (macro)

`PSA_SIGN_OUTPUT_SIZE` (macro)

`PSA_SIGNATURE_MAX_SIZE` (macro)