Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Require matching hashlen in RSA functions #4702

Closed
wants to merge 7 commits into from
Closed

Require matching hashlen in RSA functions #4702

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
7 commits
Select commit Hold shift + click to select a range
b795332
mbedtls_rsa_rsassa_pss_*: improve documentation
yanesca Apr 1, 2021
0af093b
PSA RSA PSS: pass pre-hash algorithm to Mbed TLS
yanesca Jun 7, 2021
ae50d28
Fix verify_hash tests for PSA RSA PSS
yanesca Jun 7, 2021
4c0b60e
Fix exercise key test
yanesca Jun 14, 2021
3dd3ff0
Add ChangeLog entry
yanesca Jun 15, 2021
ab97e00
Improve psa_rsa_decode_md_type()
yanesca Jun 21, 2021
e7885e5
RSA: Require hashlen to match md_alg when applicable
mpg Jun 22, 2021
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
7 changes: 7 additions & 0 deletions ChangeLog.d/psa-rsa-verify-alt-fix.txt
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,7 @@
Bugfix
* psa_verify_hash() was relying on implementation-specific behavior of
mbedtls_rsa_rsassa_pss_verify() and was causing failures in some _ALT
implementations. This reliance is now removed. Fixes #3990.
* Disallow inputs of length different from the corresponding hash when
signing or verifying with PSA_ALG_RSA_PSS (The PSA Crypto API mandates
that PSA_ALG_RSA_PSS uses the same hash throughout the algorithm.)
4 changes: 4 additions & 0 deletions ChangeLog.d/require-matching-hashlen-rsa.txt
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
API changes
* Functions in the RSA module that accept a hashlen parameter now require
it to match the output size of the hash algorithm used, except when
signing raw data.
13 changes: 13 additions & 0 deletions docs/3.0-migration-guide.d/require-matching-hashlen-rsa.md
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,13 @@
RSA signature functions now require `hashlen` to match the expected value
-------------------------------------------------------------------------

This only affects users of the low-level RSA API; users of the high-level PK
API or of the PSA Crypto API are not affected.

All the functions in the RSA module that accept a `hashlen` parameter used to
ignore it unless the `md_alg` parameter was `MBEDTLS_MD_NONE`, indicating raw
data was signed. They now require this parameter's value to be equal to the
output size of the hash algorithm used when signing a hash. (The requirements
Comment on lines +9 to +10
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think the salient point is that hashlen is now the size that is read from the buffer.

when signing raw data are unchanged.)

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

It would be convenient to have the list of affected functions:

mbedtls_rsa_pkcs1_sign
mbedtls_rsa_rsassa_pkcs1_v15_sign
mbedtls_rsa_rsassa_pss_sign_ext
mbedtls_rsa_rsassa_pss_sign
mbedtls_rsa_pkcs1_verify
mbedtls_rsa_rsassa_pkcs1_v15_verify
mbedtls_rsa_rsassa_pss_verify
mbedtls_rsa_rsassa_pss_verify_ext

The migration path is to pass the correct value to those functions.
133 changes: 61 additions & 72 deletions include/mbedtls/rsa.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -796,13 +796,11 @@ int mbedtls_rsa_rsaes_oaep_decrypt( mbedtls_rsa_context *ctx,
* if \p f_rng doesn't need a context argument.
* \param md_alg The message-digest algorithm used to hash the original data.
* Use #MBEDTLS_MD_NONE for signing raw data.
* \param hashlen The length of the message digest.
* Ths is only used if \p md_alg is #MBEDTLS_MD_NONE.
* \param hashlen The length of the message digest or raw data in Bytes.
* If \p md_alg is not #MBEDTLS_MD_NONE, this must match the
* output length of the corresponding hash algorithm.
* \param hash The buffer holding the message digest or raw data.
* If \p md_alg is #MBEDTLS_MD_NONE, this must be a readable
* buffer of length \p hashlen Bytes. If \p md_alg is not
* #MBEDTLS_MD_NONE, it must be a readable buffer of length
* the size of the hash corresponding to \p md_alg.
* This must be a readable buffer of at least \p hashlen Bytes.
* \param sig The buffer to hold the signature. This must be a writable
* buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
* for an 2048-bit RSA modulus. A buffer length of
Expand Down Expand Up @@ -830,13 +828,11 @@ int mbedtls_rsa_pkcs1_sign( mbedtls_rsa_context *ctx,
* if \p f_rng doesn't need a context argument.
* \param md_alg The message-digest algorithm used to hash the original data.
* Use #MBEDTLS_MD_NONE for signing raw data.
* \param hashlen The length of the message digest.
* Ths is only used if \p md_alg is #MBEDTLS_MD_NONE.
* \param hashlen The length of the message digest or raw data in Bytes.
* If \p md_alg is not #MBEDTLS_MD_NONE, this must match the
* output length of the corresponding hash algorithm.
* \param hash The buffer holding the message digest or raw data.
* If \p md_alg is #MBEDTLS_MD_NONE, this must be a readable
* buffer of length \p hashlen Bytes. If \p md_alg is not
* #MBEDTLS_MD_NONE, it must be a readable buffer of length
* the size of the hash corresponding to \p md_alg.
* This must be a readable buffer of at least \p hashlen Bytes.
* \param sig The buffer to hold the signature. This must be a writable
* buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
* for an 2048-bit RSA modulus. A buffer length of
Expand All @@ -857,12 +853,13 @@ int mbedtls_rsa_rsassa_pkcs1_v15_sign( mbedtls_rsa_context *ctx,
* \brief This function performs a PKCS#1 v2.1 PSS signature
* operation (RSASSA-PSS-SIGN).
*
* \note The \p hash_id in the RSA context is the one used for the
* encoding. \p md_alg in the function call is the type of hash
* that is encoded. According to <em>RFC-3447: Public-Key
* \note The \c hash_id set in \p ctx by calling
* mbedtls_rsa_set_padding() selects the hash used for the
* encoding operation and for the mask generation function
* (MGF1). For more details on the encoding operation and the
* mask generation function, consult <em>RFC-3447: Public-Key
* Cryptography Standards (PKCS) #1 v2.1: RSA Cryptography
* Specifications</em> it is advised to keep both hashes the
* same.
* Specifications</em>.
*
* \note This function enforces that the provided salt length complies
* with FIPS 186-4 §5.5 (e) and RFC 8017 (PKCS#1 v2.2) §9.1.1
Expand All @@ -877,13 +874,11 @@ int mbedtls_rsa_rsassa_pkcs1_v15_sign( mbedtls_rsa_context *ctx,
* if \p f_rng doesn't need a context argument.
* \param md_alg The message-digest algorithm used to hash the original data.
* Use #MBEDTLS_MD_NONE for signing raw data.
* \param hashlen The length of the message digest.
* Ths is only used if \p md_alg is #MBEDTLS_MD_NONE.
* \param hashlen The length of the message digest or raw data in Bytes.
* If \p md_alg is not #MBEDTLS_MD_NONE, this must match the
* output length of the corresponding hash algorithm.
* \param hash The buffer holding the message digest or raw data.
* If \p md_alg is #MBEDTLS_MD_NONE, this must be a readable
* buffer of length \p hashlen Bytes. If \p md_alg is not
* #MBEDTLS_MD_NONE, it must be a readable buffer of length
* the size of the hash corresponding to \p md_alg.
* This must be a readable buffer of at least \p hashlen Bytes.
* \param saltlen The length of the salt that should be used.
* If passed #MBEDTLS_RSA_SALT_LEN_ANY, the function will use
* the largest possible salt length up to the hash length,
Expand All @@ -910,12 +905,13 @@ int mbedtls_rsa_rsassa_pss_sign_ext( mbedtls_rsa_context *ctx,
* \brief This function performs a PKCS#1 v2.1 PSS signature
* operation (RSASSA-PSS-SIGN).
*
* \note The \p hash_id in the RSA context is the one used for the
* encoding. \p md_alg in the function call is the type of hash
* that is encoded. According to <em>RFC-3447: Public-Key
* \note The \c hash_id set in \p ctx by calling
* mbedtls_rsa_set_padding() selects the hash used for the
* encoding operation and for the mask generation function
* (MGF1). For more details on the encoding operation and the
* mask generation function, consult <em>RFC-3447: Public-Key
* Cryptography Standards (PKCS) #1 v2.1: RSA Cryptography
* Specifications</em> it is advised to keep both hashes the
* same.
* Specifications</em>.
*
* \note This function always uses the maximum possible salt size,
* up to the length of the payload hash. This choice of salt
Expand All @@ -933,13 +929,11 @@ int mbedtls_rsa_rsassa_pss_sign_ext( mbedtls_rsa_context *ctx,
* if \p f_rng doesn't need a context argument.
* \param md_alg The message-digest algorithm used to hash the original data.
* Use #MBEDTLS_MD_NONE for signing raw data.
* \param hashlen The length of the message digest.
* Ths is only used if \p md_alg is #MBEDTLS_MD_NONE.
* \param hashlen The length of the message digest or raw data in Bytes.
* If \p md_alg is not #MBEDTLS_MD_NONE, this must match the
* output length of the corresponding hash algorithm.
* \param hash The buffer holding the message digest or raw data.
* If \p md_alg is #MBEDTLS_MD_NONE, this must be a readable
* buffer of length \p hashlen Bytes. If \p md_alg is not
* #MBEDTLS_MD_NONE, it must be a readable buffer of length
* the size of the hash corresponding to \p md_alg.
* This must be a readable buffer of at least \p hashlen Bytes.
* \param sig The buffer to hold the signature. This must be a writable
* buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
* for an 2048-bit RSA modulus. A buffer length of
Expand Down Expand Up @@ -970,13 +964,11 @@ int mbedtls_rsa_rsassa_pss_sign( mbedtls_rsa_context *ctx,
* \param ctx The initialized RSA public key context to use.
* \param md_alg The message-digest algorithm used to hash the original data.
* Use #MBEDTLS_MD_NONE for signing raw data.
* \param hashlen The length of the message digest.
* This is only used if \p md_alg is #MBEDTLS_MD_NONE.
* \param hashlen The length of the message digest or raw data in Bytes.
* If \p md_alg is not #MBEDTLS_MD_NONE, this must match the
* output length of the corresponding hash algorithm.
* \param hash The buffer holding the message digest or raw data.
* If \p md_alg is #MBEDTLS_MD_NONE, this must be a readable
* buffer of length \p hashlen Bytes. If \p md_alg is not
* #MBEDTLS_MD_NONE, it must be a readable buffer of length
* the size of the hash corresponding to \p md_alg.
* This must be a readable buffer of at least \p hashlen Bytes.
* \param sig The buffer holding the signature. This must be a readable
* buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
* for an 2048-bit RSA modulus.
Expand All @@ -997,13 +989,11 @@ int mbedtls_rsa_pkcs1_verify( mbedtls_rsa_context *ctx,
* \param ctx The initialized RSA public key context to use.
* \param md_alg The message-digest algorithm used to hash the original data.
* Use #MBEDTLS_MD_NONE for signing raw data.
* \param hashlen The length of the message digest.
* This is only used if \p md_alg is #MBEDTLS_MD_NONE.
* \param hashlen The length of the message digest or raw data in Bytes.
* If \p md_alg is not #MBEDTLS_MD_NONE, this must match the
* output length of the corresponding hash algorithm.
* \param hash The buffer holding the message digest or raw data.
* If \p md_alg is #MBEDTLS_MD_NONE, this must be a readable
* buffer of length \p hashlen Bytes. If \p md_alg is not
* #MBEDTLS_MD_NONE, it must be a readable buffer of length
* the size of the hash corresponding to \p md_alg.
* This must be a readable buffer of at least \p hashlen Bytes.
* \param sig The buffer holding the signature. This must be a readable
* buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
* for an 2048-bit RSA modulus.
Expand All @@ -1021,27 +1011,24 @@ int mbedtls_rsa_rsassa_pkcs1_v15_verify( mbedtls_rsa_context *ctx,
* \brief This function performs a PKCS#1 v2.1 PSS verification
* operation (RSASSA-PSS-VERIFY).
*
* The hash function for the MGF mask generating function
* is that specified in the RSA context.
*
* \note The \p hash_id in the RSA context is the one used for the
* verification. \p md_alg in the function call is the type of
* hash that is verified. According to <em>RFC-3447: Public-Key
* \note The \c hash_id set in \p ctx by calling
* mbedtls_rsa_set_padding() selects the hash used for the
* encoding operation and for the mask generation function
* (MGF1). For more details on the encoding operation and the
* mask generation function, consult <em>RFC-3447: Public-Key
* Cryptography Standards (PKCS) #1 v2.1: RSA Cryptography
* Specifications</em> it is advised to keep both hashes the
* same. If \p hash_id in the RSA context is unset,
* the \p md_alg from the function call is used.
* Specifications</em>. If the \c hash_id set in \p ctx by
* mbedtls_rsa_set_padding() is #MBEDTLS_MD_NONE, the \p md_alg
* parameter is used.
*
* \param ctx The initialized RSA public key context to use.
* \param md_alg The message-digest algorithm used to hash the original data.
* Use #MBEDTLS_MD_NONE for signing raw data.
* \param hashlen The length of the message digest.
* This is only used if \p md_alg is #MBEDTLS_MD_NONE.
* \param hashlen The length of the message digest or raw data in Bytes.
* If \p md_alg is not #MBEDTLS_MD_NONE, this must match the
* output length of the corresponding hash algorithm.
* \param hash The buffer holding the message digest or raw data.
* If \p md_alg is #MBEDTLS_MD_NONE, this must be a readable
* buffer of length \p hashlen Bytes. If \p md_alg is not
* #MBEDTLS_MD_NONE, it must be a readable buffer of length
* the size of the hash corresponding to \p md_alg.
* This must be a readable buffer of at least \p hashlen Bytes.
* \param sig The buffer holding the signature. This must be a readable
* buffer of length \c ctx->len Bytes. For example, \c 256 Bytes
* for an 2048-bit RSA modulus.
Expand All @@ -1059,25 +1046,27 @@ int mbedtls_rsa_rsassa_pss_verify( mbedtls_rsa_context *ctx,
* \brief This function performs a PKCS#1 v2.1 PSS verification
* operation (RSASSA-PSS-VERIFY).
*
* The hash function for the MGF mask generating function
* is that specified in \p mgf1_hash_id.
*
* \note The \p sig buffer must be as large as the size
* of \p ctx->N. For example, 128 Bytes if RSA-1024 is used.
*
* \note The \p hash_id in the RSA context is ignored.
* \note The \c hash_id set in \p ctx by mbedtls_rsa_set_padding() is
* ignored.
*
* \param ctx The initialized RSA public key context to use.
* \param md_alg The message-digest algorithm used to hash the original data.
* Use #MBEDTLS_MD_NONE for signing raw data.
* \param hashlen The length of the message digest.
* This is only used if \p md_alg is #MBEDTLS_MD_NONE.
* \param hashlen The length of the message digest or raw data in Bytes.
* If \p md_alg is not #MBEDTLS_MD_NONE, this must match the
* output length of the corresponding hash algorithm.
* \param hash The buffer holding the message digest or raw data.
* If \p md_alg is #MBEDTLS_MD_NONE, this must be a readable
* buffer of length \p hashlen Bytes. If \p md_alg is not
* #MBEDTLS_MD_NONE, it must be a readable buffer of length
* the size of the hash corresponding to \p md_alg.
* \param mgf1_hash_id The message digest used for mask generation.
* This must be a readable buffer of at least \p hashlen Bytes.
* \param mgf1_hash_id The message digest algorithm used for the
* verification operation and the mask generation
* function (MGF1). For more details on the encoding
* operation and the mask generation function, consult
* <em>RFC-3447: Public-Key Cryptography Standards
* (PKCS) #1 v2.1: RSA Cryptography
* Specifications</em>.
* \param expected_salt_len The length of the salt used in padding. Use
* #MBEDTLS_RSA_SALT_LEN_ANY to accept any salt length.
* \param sig The buffer holding the signature. This must be a readable
Expand Down
19 changes: 3 additions & 16 deletions library/psa_crypto_rsa.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -360,27 +360,14 @@ static psa_status_t psa_rsa_decode_md_type( psa_algorithm_t alg,
return( PSA_ERROR_INVALID_ARGUMENT );
#endif

#if defined(BUILTIN_ALG_RSA_PKCS1V15_SIGN)
/* For PKCS#1 v1.5 signature, if using a hash, the hash length
* must be correct. */
if( PSA_ALG_IS_RSA_PKCS1V15_SIGN( alg ) &&
alg != PSA_ALG_RSA_PKCS1V15_SIGN_RAW )
/* For signatures using a hash, the hash length must be correct. */
if( alg != PSA_ALG_RSA_PKCS1V15_SIGN_RAW )
{
if( md_info == NULL )
return( PSA_ERROR_NOT_SUPPORTED );
if( mbedtls_md_get_size( md_info ) != hash_length )
return( PSA_ERROR_INVALID_ARGUMENT );
}
#endif /* BUILTIN_ALG_RSA_PKCS1V15_SIGN */

#if defined(BUILTIN_ALG_RSA_PSS)
/* PSS requires a hash internally. */
if( PSA_ALG_IS_RSA_PSS( alg ) )
{
if( md_info == NULL )
return( PSA_ERROR_NOT_SUPPORTED );
}
#endif /* BUILTIN_ALG_RSA_PSS */

return( PSA_SUCCESS );
}
Expand Down Expand Up @@ -516,7 +503,7 @@ static psa_status_t rsa_verify_hash(
if( ret == 0 )
{
ret = mbedtls_rsa_rsassa_pss_verify( rsa,
MBEDTLS_MD_NONE,
md_alg,
(unsigned int) hash_length,
hash,
signature );
Expand Down
11 changes: 6 additions & 5 deletions tests/src/psa_exercise_key.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -316,13 +316,14 @@ static int exercise_signature_key( mbedtls_svc_key_id_t key,
#endif
}

/* Some algorithms require the payload to have the size of
* the hash encoded in the algorithm. Use this input size
* even for algorithms that allow other input sizes. */
if( hash_alg != 0 )
payload_length = PSA_HASH_LENGTH( hash_alg );

if( usage & PSA_KEY_USAGE_SIGN_HASH )
{
/* Some algorithms require the payload to have the size of
* the hash encoded in the algorithm. Use this input size
* even for algorithms that allow other input sizes. */
if( hash_alg != 0 )
payload_length = PSA_HASH_LENGTH( hash_alg );
PSA_ASSERT( psa_sign_hash( key, alg,
payload, payload_length,
signature, sizeof( signature ),
Expand Down
Loading