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Key derivation: forbid output_key without input_key

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If none of the inputs to a key derivation is a
PSA_KEY_DERIVATION_INPUT_SECRET passed with
psa_key_derivation_input_key(), forbid
psa_key_derivation_output_key(). It usually doesn't make sense to
derive a key object if the secret isn't itself a proper key.
This commit is contained in:
Gilles Peskine
2019-09-24 18:21:06 +02:00
parent 1a2904c49a
commit 178c9aa966
5 changed files with 53 additions and 6 deletions
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10
library/psa_crypto.c
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@ -4787,6 +4787,9 @@ psa_status_t psa_key_derivation_output_key( const psa_key_attributes_t *attribut
if( psa_get_key_bits( attributes ) == 0 )
return( PSA_ERROR_INVALID_ARGUMENT );
if( ! operation->can_output_key )
return( PSA_ERROR_NOT_PERMITTED );
status = psa_start_key_creation( PSA_KEY_CREATION_DERIVE,
attributes, handle, &slot, &driver );
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
@ -5174,6 +5177,7 @@ psa_status_t psa_key_derivation_input_key(
{
psa_key_slot_t *slot;
psa_status_t status;
status = psa_get_transparent_key( handle, &slot,
PSA_KEY_USAGE_DERIVE,
operation->alg );
@ -5182,6 +5186,12 @@ psa_status_t psa_key_derivation_input_key(
psa_key_derivation_abort( operation );
return( status );
}
/* Passing a key object as a SECRET input unlocks the permission
* to output to a key object. */
if( step == PSA_KEY_DERIVATION_INPUT_SECRET )
operation->can_output_key = 1;
return( psa_key_derivation_input_internal( operation,
step, slot->attr.type,
slot->data.raw.data,