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Implement NormalizeLaxDERSignature in secp256k1 package

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NormalizeLaxDERSignature normalizes a Lax DER encoded signature to a
"low S" form.

See normalize_s in https://github.com/rust-bitcoin/rust-secp256k1 for an
explanation.
This commit is contained in:
Vadim Macagon 2019-01-25 23:51:56 +07:00
parent c4f3537b02
commit 92853e0183
3 changed files with 24 additions and 2 deletions
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2
crypto/secp256k1/libsecp256k1/contrib/lax_der_parsing.c
View file

@ -5,7 +5,7 @@
**********************************************************************/ **********************************************************************/
#include <string.h> #include <string.h>
#include <secp256k1.h> #include "include/secp256k1.h"
#include "lax_der_parsing.h" #include "lax_der_parsing.h"

2
crypto/secp256k1/libsecp256k1/contrib/lax_der_parsing.h
View file

@ -51,7 +51,7 @@
#ifndef _SECP256K1_CONTRIB_LAX_DER_PARSING_H_ #ifndef _SECP256K1_CONTRIB_LAX_DER_PARSING_H_
#define _SECP256K1_CONTRIB_LAX_DER_PARSING_H_ #define _SECP256K1_CONTRIB_LAX_DER_PARSING_H_
#include <secp256k1.h> #include "include/secp256k1.h"
# ifdef __cplusplus # ifdef __cplusplus
extern "C" { extern "C" {

22
crypto/secp256k1/secp256.go
View file

@ -17,6 +17,7 @@ package secp256k1
#include "./libsecp256k1/src/secp256k1.c" #include "./libsecp256k1/src/secp256k1.c"
#include "./libsecp256k1/src/modules/recovery/main_impl.h" #include "./libsecp256k1/src/modules/recovery/main_impl.h"
#include "ext.h" #include "ext.h"
#include "./libsecp256k1/contrib/lax_der_parsing.c"
typedef void (*callbackFunc) (const char* msg, void* data); typedef void (*callbackFunc) (const char* msg, void* data);
extern void secp256k1GoPanicIllegal(const char* msg, void* data); extern void secp256k1GoPanicIllegal(const char* msg, void* data);
@ -47,6 +48,7 @@ var (
ErrInvalidPubkey = errors.New("invalid public key") ErrInvalidPubkey = errors.New("invalid public key")
ErrSignFailed = errors.New("signing failed") ErrSignFailed = errors.New("signing failed")
ErrRecoverFailed = errors.New("recovery failed") ErrRecoverFailed = errors.New("recovery failed")
ErrInvalidSigEncoding = errors.New("invalid signature encoding")
) )
// Sign creates a recoverable ECDSA signature. // Sign creates a recoverable ECDSA signature.
@ -165,3 +167,23 @@ func checkSignature(sig []byte) error {
} }
return nil return nil
} }
// NormalizeLaxDERSignature normalizes a Lax DER encoded signature to a "low S" form.
// See normalize_s in https://github.com/rust-bitcoin/rust-secp256k1 for an explanation.
func NormalizeLaxDERSignature(sig []byte) ([]byte, error) {
var signature C.secp256k1_ecdsa_signature
in := (*C.uchar)(unsafe.Pointer(&sig[0]))
inLen := C.size_t(len(sig))
if C.ecdsa_signature_parse_der_lax(context, &signature, in, inLen) == 0 {
return nil, ErrInvalidSigEncoding
}
var normalizedSig C.secp256k1_ecdsa_signature
C.secp256k1_ecdsa_signature_normalize(context, &normalizedSig, &signature)
out := make([]byte, 64)
outPtr := (*C.uchar)(unsafe.Pointer(&out[0]))
C.secp256k1_ecdsa_signature_serialize_compact(context, outPtr, &normalizedSig)
return out, nil
}