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Add a hash wildcard value for hash-and-sign algorithm

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You can use PSA_ALG_ANY_HASH to build the algorithm value for a
hash-and-sign algorithm in a policy. Then the policy allows usage with
this hash-and-sign family with any hash.

Test that PSA_ALG_ANY_HASH-based policies allow a specific hash, but
not a different hash-and-sign family. Test that PSA_ALG_ANY_HASH is
not valid for operations, only in policies.
This commit is contained in:
Gilles Peskine 2019-01-14 16:06:39 +01:00
parent d35b489ce5
commit 30f77cdfc1
6 changed files with 180 additions and 16 deletions
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64
include/psa/crypto_values.h
View file

@ -641,6 +641,7 @@
(((alg) & PSA_ALG_CATEGORY_MASK) == PSA_ALG_CATEGORY_KEY_SELECTION)
#define PSA_ALG_HASH_MASK ((psa_algorithm_t)0x000000ff)
#define PSA_ALG_MD2 ((psa_algorithm_t)0x01000001)
#define PSA_ALG_MD4 ((psa_algorithm_t)0x01000002)
#define PSA_ALG_MD5 ((psa_algorithm_t)0x01000003)
@ -667,6 +668,41 @@
/** SHA3-512 */
#define PSA_ALG_SHA3_512 ((psa_algorithm_t)0x01000013)
/** Allow any hash algorithm.
*
* This value may only be used to form the algorithm usage field of a policy
* for a signature algorithm that is parametrized by a 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_DSA, #PSA_ALG_DETERMINISTIC_DSA,
* - #PSA_ALG_ECDSA, #PSA_ALG_DETERMINISTIC_ECDSA.
* Then you may create a key as follows:
* - Set the key usage field using #PSA_ALG_ANY_HASH, for example:
* ```
* psa_key_policy_set_usage(&policy,
* PSA_KEY_USAGE_SIGN, //or PSA_KEY_USAGE_VERIFY
* PSA_xxx_SIGNATURE(PSA_ALG_ANY_HASH));
* psa_set_key_policy(handle, &policy);
* ```
* - Import or generate key material.
* - Call psa_asymmetric_sign() or psa_asymmetric_verify(), 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_asymmetric_sign(handle, PSA_xxx_SIGNATURE(PSA_ALG_SHA_256), ...);
* psa_asymmetric_sign(handle, PSA_xxx_SIGNATURE(PSA_ALG_SHA_512), ...);
* psa_asymmetric_sign(handle, 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 `\p alg`, #PSA_ALG_IS_HASH_AND_SIGN(\p 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.
*/
#define PSA_ALG_ANY_HASH ((psa_algorithm_t)0x010000ff)
#define PSA_ALG_MAC_SUBCATEGORY_MASK ((psa_algorithm_t)0x00c00000)
#define PSA_ALG_HMAC_BASE ((psa_algorithm_t)0x02800000)
/** Macro to build an HMAC algorithm.
@ -914,6 +950,8 @@
*
* \param hash_alg A hash algorithm (\c PSA_ALG_XXX value such that
* #PSA_ALG_IS_HASH(\p hash_alg) is true).
* This includes #PSA_ALG_ANY_HASH
* when specifying the algorithm in a usage policy.
*
* \return The corresponding RSA PKCS#1 v1.5 signature algorithm.
* \return Unspecified if \p alg is not a supported
@ -943,6 +981,8 @@
*
* \param hash_alg A hash algorithm (\c PSA_ALG_XXX value such that
* #PSA_ALG_IS_HASH(\p hash_alg) is true).
* This includes #PSA_ALG_ANY_HASH
* when specifying the algorithm in a usage policy.
*
* \return The corresponding RSA PSS signature algorithm.
* \return Unspecified if \p alg is not a supported
@ -961,6 +1001,8 @@
*
* \param hash_alg A hash algorithm (\c PSA_ALG_XXX value such that
* #PSA_ALG_IS_HASH(\p hash_alg) is true).
* This includes #PSA_ALG_ANY_HASH
* when specifying the algorithm in a usage policy.
*
* \return The corresponding DSA signature algorithm.
* \return Unspecified if \p alg is not a supported
@ -996,6 +1038,8 @@
*
* \param hash_alg A hash algorithm (\c PSA_ALG_XXX value such that
* #PSA_ALG_IS_HASH(\p hash_alg) is true).
* This includes #PSA_ALG_ANY_HASH
* when specifying the algorithm in a usage policy.
*
* \return The corresponding ECDSA signature algorithm.
* \return Unspecified if \p alg is not a supported
@ -1028,6 +1072,8 @@
*
* \param hash_alg A hash algorithm (\c PSA_ALG_XXX value such that
* #PSA_ALG_IS_HASH(\p hash_alg) is true).
* This includes #PSA_ALG_ANY_HASH
* when specifying the algorithm in a usage policy.
*
* \return The corresponding deterministic ECDSA signature
* algorithm.
@ -1341,6 +1387,24 @@
#define PSA_ALG_IS_ECDH(alg) \
(PSA_ALG_KEY_AGREEMENT_GET_BASE(alg) == PSA_ALG_ECDH_BASE)
/** 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.
*
* \param alg An algorithm identifier (value of type #psa_algorithm_t).
*
* \return 1 if \c alg is a wildcard algorithm encoding.
* \return 0 if \c alg is a non-wildcard algorithm encoding (suitable for
* an operation).
* \return This macro may return either 0 or 1 if \c alg is not a supported
* algorithm identifier.
*/
#define PSA_ALG_IS_WILDCARD(alg) \
(PSA_ALG_IS_HASH_AND_SIGN(alg) ? \
PSA_ALG_SIGN_GET_HASH(alg) == PSA_ALG_ANY_HASH : \
(alg) == PSA_ALG_ANY_HASH)
/**@}*/
/** \defgroup key_lifetimes Key lifetimes