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RSA PSS OpenSSL compatibility verification: support AUTO #6938

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Merged
dgarske merged 1 commit into from
Nov 2, 2023
Merged

RSA PSS OpenSSL compatibility verification: support AUTO #6938

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7 changes: 5 additions & 2 deletions src/pk.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3556,13 +3556,16 @@ int wolfSSL_RSA_verify_PKCS1_PSS(WOLFSSL_RSA *rsa, const unsigned char *mHash,

if (ret == 1) {
/* Calculate the salt length to use for special cases. */
/* TODO: use special case wolfCrypt values. */
switch (saltLen) {
/* Negative saltLen values are treated differently */
case RSA_PSS_SALTLEN_DIGEST:
saltLen = hashLen;
break;
case RSA_PSS_SALTLEN_MAX_SIGN:
case RSA_PSS_SALTLEN_AUTO:
#ifdef WOLFSSL_PSS_SALT_LEN_DISCOVER
saltLen = RSA_PSS_SALT_LEN_DISCOVER;
break;
#endif
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@dgarske dgarske Nov 1, 2023

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Perhaps the #else case should return an error?

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@SparkiDev SparkiDev Nov 2, 2023

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No case now when WOLFSSL_PSS_SALT_LEN_DISCOVER not defined.
Will go to default which errors out on negative.

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@dgarske dgarske Nov 2, 2023

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I'd really like a test case for this... Could we add one?

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@SparkiDev SparkiDev Nov 2, 2023

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Actually that doesn't work.
-2 is RSA_PSS_SALTLEN_MAX_SIGN for signing and using -2 should have the same semantics in verify.
Discovery will handle anything.

case RSA_PSS_SALTLEN_MAX:
#ifdef WOLFSSL_PSS_LONG_SALT
saltLen = emLen - hashLen - 2;
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2 changes: 2 additions & 0 deletions wolfssl/openssl/rsa.h
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Expand Up @@ -54,6 +54,8 @@
#define RSA_PSS_SALTLEN_DIGEST (-1)
/* Old max salt length */
#define RSA_PSS_SALTLEN_MAX_SIGN (-2)
/* Verification only value to indicate to discover salt length. */
#define RSA_PSS_SALTLEN_AUTO (-2)
/* Max salt length */
#define RSA_PSS_SALTLEN_MAX (-3)
#endif /* OPENSSL_EXTRA || OPENSSL_EXTRA_X509_SMALL */
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