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椭圆曲线公钥转换为比特币地址原理

2016-10-21 20:21 330 查看

Assuming what you're doing is based on this conversion:

I'll describe what you can do in pseudo-code:

First extract x, y from public key.

// get x and y from Public key "point"
EC_POINT_get_affine_coordinates_GFp(group, pub_key, x, y, ctx);
// convert BIGNUMs x, y into binary form
BN_bn2bin(x,x_char);
BN_bn2bin(y,y_char);

Next you need to do message digest several times, including 3 sha256 and 1 ripemd160. In the following pseudo-code I'll show you how to do ripemd160. To do sha256 with EVP_MD, just replace

EVP_ripemd160()

with

EVP_sha256()

,
and update (input to EVP_MD) your input message with single or several

EVP_DigestUpdate()

EVP_MD_CTX ctx;
EVP_MD_CTX_init(&md_ctx);
EVP_DigestInit(&md_ctx, EVP_ripemd160());
// hdr = 0x04
EVP_DigestUpdate(&md_ctx,hdr,1);
EVP_DigestUpdate(&md_ctx,x_char,32);
EVP_DigestUpdate(&md_ctx,y_char,32);
// put message degest into dgst and set length to dgstlen
EVP_DigestFinal(&md_ctx,dgst,&dgstlen);
EVP_MD_CTX_cleanup(&md_ctx);

Or the easier way, call

sha256()

and

ripemd160()

directly.
But you need to prepare your input message before calling hash functions

sha256()

ripemd160()

.

The 25-byte binary address is the result of ripemd160, together with the first 4 bytes of 32-byte checksum. You need to find a way to convert it from Base 256 to Base 58. I don't think OpenSSL support that.

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this answer

answered Jul 17 '13 at 2:56

ChiaraHsieh
2,0241230

Assuming what you're doing is based on this conversion:

I'll describe what you can do in pseudo-code:

First extract x, y from public key.

// get x and y from Public key "point"
EC_POINT_get_affine_coordinates_GFp(group, pub_key, x, y, ctx);
// convert BIGNUMs x, y into binary form
BN_bn2bin(x,x_char);
BN_bn2bin(y,y_char);

Next you need to do message digest several times, including 3 sha256 and 1 ripemd160. In the following pseudo-code I'll show you how to do ripemd160. To do sha256 with EVP_MD, just replace

EVP_ripemd160()

with

EVP_sha256()

,
and update (input to EVP_MD) your input message with single or several

EVP_DigestUpdate()

EVP_MD_CTX ctx;
EVP_MD_CTX_init(&md_ctx);
EVP_DigestInit(&md_ctx, EVP_ripemd160());
// hdr = 0x04
EVP_DigestUpdate(&md_ctx,hdr,1);
EVP_DigestUpdate(&md_ctx,x_char,32);
EVP_DigestUpdate(&md_ctx,y_char,32);
// put message degest into dgst and set length to dgstlen
EVP_DigestFinal(&md_ctx,dgst,&dgstlen);
EVP_MD_CTX_cleanup(&md_ctx);

Or the easier way, call

sha256()

and

ripemd160()

directly.
But you need to prepare your input message before calling hash functions

sha256()

ripemd160()

shareimprove
this answer

answered Jul 17 '13 at 2:56

ChiaraHsieh
2,0241230

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