diff mbox series

[06/12] crypto: ecdsa - Support P1363 signature encoding

Message ID 4f98bb7ee2e660a8b4513a94ed79f4f29d1ff379.1695921657.git.lukas@wunner.de (mailing list archive)
State Changes Requested
Delegated to: Bjorn Helgaas
Headers show
Series PCI device authentication | expand

Commit Message

Lukas Wunner Sept. 28, 2023, 5:32 p.m. UTC
Alternatively to the X9.62 encoding of ecdsa signatures, which uses
ASN.1 and is already supported by the kernel, there's another common
encoding called P1363.  It stores r and s as the concatenation of two
big endian, unsigned integers.  The name originates from IEEE P1363.

The Security Protocol and Data Model (SPDM) specification prescribes
that ecdsa signatures are encoded according to P1363:

   "For ECDSA signatures, excluding SM2, in SPDM, the signature shall be
    the concatenation of r and s.  The size of r shall be the size of
    the selected curve.  Likewise, the size of s shall be the size of
    the selected curve.  See BaseAsymAlgo in NEGOTIATE_ALGORITHMS for
    the size of r and s.  The byte order for r and s shall be in big
    endian order.  When placing ECDSA signatures into an SPDM signature
    field, r shall come first followed by s."

    (SPDM 1.2.1 margin no 44,
    https://www.dmtf.org/sites/default/files/standards/documents/DSP0274_1.2.1.pdf)

A subsequent commit introduces an SPDM library to enable PCI device
authentication, so add support for P1363 ecdsa signature verification.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
---
 crypto/asymmetric_keys/public_key.c |  8 ++++++--
 crypto/ecdsa.c                      | 16 +++++++++++++---
 crypto/testmgr.h                    | 15 +++++++++++++++
 3 files changed, 34 insertions(+), 5 deletions(-)

Comments

Jonathan Cameron Oct. 2, 2023, 4:57 p.m. UTC | #1
On Thu, 28 Sep 2023 19:32:36 +0200
Lukas Wunner <lukas@wunner.de> wrote:

> Alternatively to the X9.62 encoding of ecdsa signatures, which uses
> ASN.1 and is already supported by the kernel, there's another common
> encoding called P1363.  It stores r and s as the concatenation of two
> big endian, unsigned integers.  The name originates from IEEE P1363.
> 
> The Security Protocol and Data Model (SPDM) specification prescribes
> that ecdsa signatures are encoded according to P1363:
> 
>    "For ECDSA signatures, excluding SM2, in SPDM, the signature shall be
>     the concatenation of r and s.  The size of r shall be the size of
>     the selected curve.  Likewise, the size of s shall be the size of
>     the selected curve.  See BaseAsymAlgo in NEGOTIATE_ALGORITHMS for
>     the size of r and s.  The byte order for r and s shall be in big
>     endian order.  When placing ECDSA signatures into an SPDM signature
>     field, r shall come first followed by s."
> 
>     (SPDM 1.2.1 margin no 44,
>     https://www.dmtf.org/sites/default/files/standards/documents/DSP0274_1.2.1.pdf)
> 
> A subsequent commit introduces an SPDM library to enable PCI device
> authentication, so add support for P1363 ecdsa signature verification.

Ah good. The spec got updated. I remember playing guess with the format
against libspdm which wasn't fun :)

One trivial formatting note inline.

> 
> Signed-off-by: Lukas Wunner <lukas@wunner.de>

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>


> ---
>  crypto/asymmetric_keys/public_key.c |  8 ++++++--
>  crypto/ecdsa.c                      | 16 +++++++++++++---
>  crypto/testmgr.h                    | 15 +++++++++++++++
>  3 files changed, 34 insertions(+), 5 deletions(-)
> 
> diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
> index 7f96e8e501db..84c4ed02a270 100644
> --- a/crypto/asymmetric_keys/public_key.c
> +++ b/crypto/asymmetric_keys/public_key.c
> @@ -105,7 +105,8 @@ software_key_determine_akcipher(const struct public_key *pkey,
>  			return -EINVAL;
>  		*sig = false;
>  	} else if (strncmp(pkey->pkey_algo, "ecdsa", 5) == 0) {
> -		if (strcmp(encoding, "x962") != 0)
> +		if (strcmp(encoding, "x962") != 0 &&
> +		    strcmp(encoding, "p1363") != 0)
>  			return -EINVAL;
>  		/*
>  		 * ECDSA signatures are taken over a raw hash, so they don't
> @@ -246,7 +247,10 @@ static int software_key_query(const struct kernel_pkey_params *params,
>  		 * which is actually 2 'key_size'-bit integers encoded in
>  		 * ASN.1.  Account for the ASN.1 encoding overhead here.
>  		 */
> -		info->max_sig_size = 2 * (len + 3) + 2;
> +		if (strcmp(params->encoding, "x962") == 0)
> +			info->max_sig_size = 2 * (len + 3) + 2;
> +		else if (strcmp(params->encoding, "p1363") == 0)
> +			info->max_sig_size = 2 * len;
>  	} else {
>  		info->max_data_size = len;
>  		info->max_sig_size = len;
> diff --git a/crypto/ecdsa.c b/crypto/ecdsa.c
> index fbd76498aba8..cc3082c6f67d 100644
> --- a/crypto/ecdsa.c
> +++ b/crypto/ecdsa.c
> @@ -159,10 +159,20 @@ static int ecdsa_verify(struct akcipher_request *req)
>  		sg_nents_for_len(req->src, req->src_len + req->dst_len),
>  		buffer, req->src_len + req->dst_len, 0);
>  
> -	ret = asn1_ber_decoder(&ecdsasignature_decoder, &sig_ctx,
> -			       buffer, req->src_len);
> -	if (ret < 0)
> +	if (strcmp(req->enc, "x962") == 0) {
> +		ret = asn1_ber_decoder(&ecdsasignature_decoder, &sig_ctx,
> +				       buffer, req->src_len);
> +		if (ret < 0)
> +			goto error;
> +	} else if (strcmp(req->enc, "p1363") == 0 &&
> +		   req->src_len == 2 * keylen) {
> +		ecc_swap_digits(buffer, sig_ctx.r, ctx->curve->g.ndigits);
> +		ecc_swap_digits(buffer + keylen,
> +					sig_ctx.s, ctx->curve->g.ndigits);

Indent looks a little odd.


> +	} else {
> +		ret = -EINVAL;
>  		goto error;
> +	}
>  
>  	/* if the hash is shorter then we will add leading zeros to fit to ndigits */
>  	diff = keylen - req->dst_len;
> diff --git a/crypto/testmgr.h b/crypto/testmgr.h
> index ad57e7af2e14..f12f70818147 100644
> --- a/crypto/testmgr.h
> +++ b/crypto/testmgr.h
> @@ -674,6 +674,7 @@ static const struct akcipher_testvec ecdsa_nist_p192_tv_template[] = {
>  	"\x68\x01\x9d\xba\xce\x83\x08\xef\x95\x52\x7b\xa0\x0f\xe4\x18\x86"
>  	"\x80\x6f\xa5\x79\x77\xda\xd0",
>  	.c_size = 55,
> +	.enc = "x962",
>  	.public_key_vec = true,
>  	.siggen_sigver_test = true,
>  	}, {
> @@ -698,6 +699,7 @@ static const struct akcipher_testvec ecdsa_nist_p192_tv_template[] = {
>  	"\x4f\x53\x75\xc8\x02\x48\xeb\xc3\x92\x0f\x1e\x72\xee\xc4\xa3\xe3"
>  	"\x5c\x99\xdb\x92\x5b\x36",
>  	.c_size = 54,
> +	.enc = "x962",
>  	.public_key_vec = true,
>  	.siggen_sigver_test = true,
>  	}, {
> @@ -722,6 +724,7 @@ static const struct akcipher_testvec ecdsa_nist_p192_tv_template[] = {
>  	"\x69\x43\xfd\x48\x19\x86\xcf\x32\xdd\x41\x74\x6a\x51\xc7\xd9\x7d"
>  	"\x3a\x97\xd9\xcd\x1a\x6a\x49",
>  	.c_size = 55,
> +	.enc = "x962",
>  	.public_key_vec = true,
>  	.siggen_sigver_test = true,
>  	}, {
> @@ -747,6 +750,7 @@ static const struct akcipher_testvec ecdsa_nist_p192_tv_template[] = {
>  	"\xbc\x5a\x1f\x82\x96\x61\xd7\xd1\x01\x77\x44\x5d\x53\xa4\x7c\x93"
>  	"\x12\x3b\x3b\x28\xfb\x6d\xe1",
>  	.c_size = 55,
> +	.enc = "x962",
>  	.public_key_vec = true,
>  	.siggen_sigver_test = true,
>  	}, {
> @@ -773,6 +777,7 @@ static const struct akcipher_testvec ecdsa_nist_p192_tv_template[] = {
>  	"\xb4\x22\x9a\x98\x73\x3c\x83\xa9\x14\x2a\x5e\xf5\xe5\xfb\x72\x28"
>  	"\x6a\xdf\x97\xfd\x82\x76\x24",
>  	.c_size = 55,
> +	.enc = "x962",
>  	.public_key_vec = true,
>  	.siggen_sigver_test = true,
>  	},
> @@ -803,6 +808,7 @@ static const struct akcipher_testvec ecdsa_nist_p256_tv_template[] = {
>  	"\x8a\xfa\x54\x93\x29\xa7\x70\x86\xf1\x03\x03\xf3\x3b\xe2\x73\xf7"
>  	"\xfb\x9d\x8b\xde\xd4\x8d\x6f\xad",
>  	.c_size = 72,
> +	.enc = "x962",
>  	.public_key_vec = true,
>  	.siggen_sigver_test = true,
>  	}, {
> @@ -829,6 +835,7 @@ static const struct akcipher_testvec ecdsa_nist_p256_tv_template[] = {
>  	"\x4a\x77\x22\xec\xc8\x66\xbf\x50\x05\x58\x39\x0e\x26\x92\xce\xd5"
>  	"\x2e\x8b\xde\x5a\x04\x0e",
>  	.c_size = 70,
> +	.enc = "x962",
>  	.public_key_vec = true,
>  	.siggen_sigver_test = true,
>  	}, {
> @@ -855,6 +862,7 @@ static const struct akcipher_testvec ecdsa_nist_p256_tv_template[] = {
>  	"\xa9\x81\xac\x4a\x50\xd0\x91\x0a\x6e\x1b\xc4\xaf\xe1\x83\xc3\x4f"
>  	"\x2a\x65\x35\x23\xe3\x1d\xfa",
>  	.c_size = 71,
> +	.enc = "x962",
>  	.public_key_vec = true,
>  	.siggen_sigver_test = true,
>  	}, {
> @@ -882,6 +890,7 @@ static const struct akcipher_testvec ecdsa_nist_p256_tv_template[] = {
>  	"\x19\xfb\x5f\x92\xf4\xc9\x23\x37\x69\xf4\x3b\x4f\x47\xcf\x9b\x16"
>  	"\xc0\x60\x11\x92\xdc\x17\x89\x12",
>  	.c_size = 72,
> +	.enc = "x962",
>  	.public_key_vec = true,
>  	.siggen_sigver_test = true,
>  	}, {
> @@ -910,6 +919,7 @@ static const struct akcipher_testvec ecdsa_nist_p256_tv_template[] = {
>  	"\x00\xdd\xab\xd4\xc0\x2b\xe6\x5c\xad\xc3\x78\x1c\xc2\xc1\x19\x76"
>  	"\x31\x79\x4a\xe9\x81\x6a\xee",
>  	.c_size = 71,
> +	.enc = "x962",
>  	.public_key_vec = true,
>  	.siggen_sigver_test = true,
>  	},
> @@ -944,6 +954,7 @@ static const struct akcipher_testvec ecdsa_nist_p384_tv_template[] = {
>  	"\x74\xa0\x0f\xbf\xaf\xc3\x36\x76\x4a\xa1\x59\xf1\x1c\xa4\x58\x26"
>  	"\x79\x12\x2a\xb7\xc5\x15\x92\xc5",
>  	.c_size = 104,
> +	.enc = "x962",
>  	.public_key_vec = true,
>  	.siggen_sigver_test = true,
>  	}, {
> @@ -974,6 +985,7 @@ static const struct akcipher_testvec ecdsa_nist_p384_tv_template[] = {
>  	"\x4d\xd0\xc6\x6e\xb0\xe9\xfc\x14\x9f\x19\xd0\x42\x8b\x93\xc2\x11"
>  	"\x88\x2b\x82\x26\x5e\x1c\xda\xfb",
>  	.c_size = 104,
> +	.enc = "x962",
>  	.public_key_vec = true,
>  	.siggen_sigver_test = true,
>  	}, {
> @@ -1004,6 +1016,7 @@ static const struct akcipher_testvec ecdsa_nist_p384_tv_template[] = {
>  	"\xc0\x75\x3e\x23\x5e\x36\x4f\x8d\xde\x1e\x93\x8d\x95\xbb\x10\x0e"
>  	"\xf4\x1f\x39\xca\x4d\x43",
>  	.c_size = 102,
> +	.enc = "x962",
>  	.public_key_vec = true,
>  	.siggen_sigver_test = true,
>  	}, {
> @@ -1035,6 +1048,7 @@ static const struct akcipher_testvec ecdsa_nist_p384_tv_template[] = {
>  	"\x44\x92\x8c\x86\x99\x65\xb3\x97\x96\x17\x04\xc9\x05\x77\xf1\x8e"
>  	"\xab\x8d\x4e\xde\xe6\x6d\x9b\x66",
>  	.c_size = 104,
> +	.enc = "x962",
>  	.public_key_vec = true,
>  	.siggen_sigver_test = true,
>  	}, {
> @@ -1067,6 +1081,7 @@ static const struct akcipher_testvec ecdsa_nist_p384_tv_template[] = {
>  	"\x5f\x8d\x7a\xf9\xfb\x34\xe4\x8b\x80\xa5\xb6\xda\x2c\x4e\x45\xcf"
>  	"\x3c\x93\xff\x50\x5d",
>  	.c_size = 101,
> +	.enc = "x962",
>  	.public_key_vec = true,
>  	.siggen_sigver_test = true,
>  	},
diff mbox series

Patch

diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
index 7f96e8e501db..84c4ed02a270 100644
--- a/crypto/asymmetric_keys/public_key.c
+++ b/crypto/asymmetric_keys/public_key.c
@@ -105,7 +105,8 @@  software_key_determine_akcipher(const struct public_key *pkey,
 			return -EINVAL;
 		*sig = false;
 	} else if (strncmp(pkey->pkey_algo, "ecdsa", 5) == 0) {
-		if (strcmp(encoding, "x962") != 0)
+		if (strcmp(encoding, "x962") != 0 &&
+		    strcmp(encoding, "p1363") != 0)
 			return -EINVAL;
 		/*
 		 * ECDSA signatures are taken over a raw hash, so they don't
@@ -246,7 +247,10 @@  static int software_key_query(const struct kernel_pkey_params *params,
 		 * which is actually 2 'key_size'-bit integers encoded in
 		 * ASN.1.  Account for the ASN.1 encoding overhead here.
 		 */
-		info->max_sig_size = 2 * (len + 3) + 2;
+		if (strcmp(params->encoding, "x962") == 0)
+			info->max_sig_size = 2 * (len + 3) + 2;
+		else if (strcmp(params->encoding, "p1363") == 0)
+			info->max_sig_size = 2 * len;
 	} else {
 		info->max_data_size = len;
 		info->max_sig_size = len;
diff --git a/crypto/ecdsa.c b/crypto/ecdsa.c
index fbd76498aba8..cc3082c6f67d 100644
--- a/crypto/ecdsa.c
+++ b/crypto/ecdsa.c
@@ -159,10 +159,20 @@  static int ecdsa_verify(struct akcipher_request *req)
 		sg_nents_for_len(req->src, req->src_len + req->dst_len),
 		buffer, req->src_len + req->dst_len, 0);
 
-	ret = asn1_ber_decoder(&ecdsasignature_decoder, &sig_ctx,
-			       buffer, req->src_len);
-	if (ret < 0)
+	if (strcmp(req->enc, "x962") == 0) {
+		ret = asn1_ber_decoder(&ecdsasignature_decoder, &sig_ctx,
+				       buffer, req->src_len);
+		if (ret < 0)
+			goto error;
+	} else if (strcmp(req->enc, "p1363") == 0 &&
+		   req->src_len == 2 * keylen) {
+		ecc_swap_digits(buffer, sig_ctx.r, ctx->curve->g.ndigits);
+		ecc_swap_digits(buffer + keylen,
+					sig_ctx.s, ctx->curve->g.ndigits);
+	} else {
+		ret = -EINVAL;
 		goto error;
+	}
 
 	/* if the hash is shorter then we will add leading zeros to fit to ndigits */
 	diff = keylen - req->dst_len;
diff --git a/crypto/testmgr.h b/crypto/testmgr.h
index ad57e7af2e14..f12f70818147 100644
--- a/crypto/testmgr.h
+++ b/crypto/testmgr.h
@@ -674,6 +674,7 @@  static const struct akcipher_testvec ecdsa_nist_p192_tv_template[] = {
 	"\x68\x01\x9d\xba\xce\x83\x08\xef\x95\x52\x7b\xa0\x0f\xe4\x18\x86"
 	"\x80\x6f\xa5\x79\x77\xda\xd0",
 	.c_size = 55,
+	.enc = "x962",
 	.public_key_vec = true,
 	.siggen_sigver_test = true,
 	}, {
@@ -698,6 +699,7 @@  static const struct akcipher_testvec ecdsa_nist_p192_tv_template[] = {
 	"\x4f\x53\x75\xc8\x02\x48\xeb\xc3\x92\x0f\x1e\x72\xee\xc4\xa3\xe3"
 	"\x5c\x99\xdb\x92\x5b\x36",
 	.c_size = 54,
+	.enc = "x962",
 	.public_key_vec = true,
 	.siggen_sigver_test = true,
 	}, {
@@ -722,6 +724,7 @@  static const struct akcipher_testvec ecdsa_nist_p192_tv_template[] = {
 	"\x69\x43\xfd\x48\x19\x86\xcf\x32\xdd\x41\x74\x6a\x51\xc7\xd9\x7d"
 	"\x3a\x97\xd9\xcd\x1a\x6a\x49",
 	.c_size = 55,
+	.enc = "x962",
 	.public_key_vec = true,
 	.siggen_sigver_test = true,
 	}, {
@@ -747,6 +750,7 @@  static const struct akcipher_testvec ecdsa_nist_p192_tv_template[] = {
 	"\xbc\x5a\x1f\x82\x96\x61\xd7\xd1\x01\x77\x44\x5d\x53\xa4\x7c\x93"
 	"\x12\x3b\x3b\x28\xfb\x6d\xe1",
 	.c_size = 55,
+	.enc = "x962",
 	.public_key_vec = true,
 	.siggen_sigver_test = true,
 	}, {
@@ -773,6 +777,7 @@  static const struct akcipher_testvec ecdsa_nist_p192_tv_template[] = {
 	"\xb4\x22\x9a\x98\x73\x3c\x83\xa9\x14\x2a\x5e\xf5\xe5\xfb\x72\x28"
 	"\x6a\xdf\x97\xfd\x82\x76\x24",
 	.c_size = 55,
+	.enc = "x962",
 	.public_key_vec = true,
 	.siggen_sigver_test = true,
 	},
@@ -803,6 +808,7 @@  static const struct akcipher_testvec ecdsa_nist_p256_tv_template[] = {
 	"\x8a\xfa\x54\x93\x29\xa7\x70\x86\xf1\x03\x03\xf3\x3b\xe2\x73\xf7"
 	"\xfb\x9d\x8b\xde\xd4\x8d\x6f\xad",
 	.c_size = 72,
+	.enc = "x962",
 	.public_key_vec = true,
 	.siggen_sigver_test = true,
 	}, {
@@ -829,6 +835,7 @@  static const struct akcipher_testvec ecdsa_nist_p256_tv_template[] = {
 	"\x4a\x77\x22\xec\xc8\x66\xbf\x50\x05\x58\x39\x0e\x26\x92\xce\xd5"
 	"\x2e\x8b\xde\x5a\x04\x0e",
 	.c_size = 70,
+	.enc = "x962",
 	.public_key_vec = true,
 	.siggen_sigver_test = true,
 	}, {
@@ -855,6 +862,7 @@  static const struct akcipher_testvec ecdsa_nist_p256_tv_template[] = {
 	"\xa9\x81\xac\x4a\x50\xd0\x91\x0a\x6e\x1b\xc4\xaf\xe1\x83\xc3\x4f"
 	"\x2a\x65\x35\x23\xe3\x1d\xfa",
 	.c_size = 71,
+	.enc = "x962",
 	.public_key_vec = true,
 	.siggen_sigver_test = true,
 	}, {
@@ -882,6 +890,7 @@  static const struct akcipher_testvec ecdsa_nist_p256_tv_template[] = {
 	"\x19\xfb\x5f\x92\xf4\xc9\x23\x37\x69\xf4\x3b\x4f\x47\xcf\x9b\x16"
 	"\xc0\x60\x11\x92\xdc\x17\x89\x12",
 	.c_size = 72,
+	.enc = "x962",
 	.public_key_vec = true,
 	.siggen_sigver_test = true,
 	}, {
@@ -910,6 +919,7 @@  static const struct akcipher_testvec ecdsa_nist_p256_tv_template[] = {
 	"\x00\xdd\xab\xd4\xc0\x2b\xe6\x5c\xad\xc3\x78\x1c\xc2\xc1\x19\x76"
 	"\x31\x79\x4a\xe9\x81\x6a\xee",
 	.c_size = 71,
+	.enc = "x962",
 	.public_key_vec = true,
 	.siggen_sigver_test = true,
 	},
@@ -944,6 +954,7 @@  static const struct akcipher_testvec ecdsa_nist_p384_tv_template[] = {
 	"\x74\xa0\x0f\xbf\xaf\xc3\x36\x76\x4a\xa1\x59\xf1\x1c\xa4\x58\x26"
 	"\x79\x12\x2a\xb7\xc5\x15\x92\xc5",
 	.c_size = 104,
+	.enc = "x962",
 	.public_key_vec = true,
 	.siggen_sigver_test = true,
 	}, {
@@ -974,6 +985,7 @@  static const struct akcipher_testvec ecdsa_nist_p384_tv_template[] = {
 	"\x4d\xd0\xc6\x6e\xb0\xe9\xfc\x14\x9f\x19\xd0\x42\x8b\x93\xc2\x11"
 	"\x88\x2b\x82\x26\x5e\x1c\xda\xfb",
 	.c_size = 104,
+	.enc = "x962",
 	.public_key_vec = true,
 	.siggen_sigver_test = true,
 	}, {
@@ -1004,6 +1016,7 @@  static const struct akcipher_testvec ecdsa_nist_p384_tv_template[] = {
 	"\xc0\x75\x3e\x23\x5e\x36\x4f\x8d\xde\x1e\x93\x8d\x95\xbb\x10\x0e"
 	"\xf4\x1f\x39\xca\x4d\x43",
 	.c_size = 102,
+	.enc = "x962",
 	.public_key_vec = true,
 	.siggen_sigver_test = true,
 	}, {
@@ -1035,6 +1048,7 @@  static const struct akcipher_testvec ecdsa_nist_p384_tv_template[] = {
 	"\x44\x92\x8c\x86\x99\x65\xb3\x97\x96\x17\x04\xc9\x05\x77\xf1\x8e"
 	"\xab\x8d\x4e\xde\xe6\x6d\x9b\x66",
 	.c_size = 104,
+	.enc = "x962",
 	.public_key_vec = true,
 	.siggen_sigver_test = true,
 	}, {
@@ -1067,6 +1081,7 @@  static const struct akcipher_testvec ecdsa_nist_p384_tv_template[] = {
 	"\x5f\x8d\x7a\xf9\xfb\x34\xe4\x8b\x80\xa5\xb6\xda\x2c\x4e\x45\xcf"
 	"\x3c\x93\xff\x50\x5d",
 	.c_size = 101,
+	.enc = "x962",
 	.public_key_vec = true,
 	.siggen_sigver_test = true,
 	},