SHA256で秘密鍵と公開鍵の生成とデジタル署名

はじめに

ブロックチェーンで使用される基本的な暗号技術の秘密鍵や公開鍵の作成をしてみたので、その備忘録です。

秘密鍵、公開鍵の作成

秘密鍵の作成

$ openssl ecparam -genkey -name secp256k1 -out private.pem
$ cat private.pem
-----BEGIN EC PARAMETERS-----
BgUrgQQACg==
-----END EC PARAMETERS-----
-----BEGIN EC PRIVATE KEY-----
MHQCAQEEIAp9S1sZ+vZlujoXq09cHKxVoXgvEM9XebEXYSgbjKXdoAcGBSuBBAAK
oUQDQgAESSnAL8MsfVWbqPVvNgggO4cvi2XfG/uQ9Jwh57tDqTN3ssHR/ZOYHv2J
kLr2Z+mMpdok/Ir5dHsblowNLxdw7g==
-----END EC PRIVATE KEY-----

公開鍵の作成

$ openssl ec -in private.pem -pubout -out public.pem
read EC key
writing EC key
$ cat public.pem
-----BEGIN PUBLIC KEY-----
MFYwEAYHKoZIzj0CAQYFK4EEAAoDQgAESSnAL8MsfVWbqPVvNgggO4cvi2XfG/uQ
9Jwh57tDqTN3ssHR/ZOYHv2JkLr2Z+mMpdok/Ir5dHsblowNLxdw7g==
-----END PUBLIC KEY-----

デジタル署名

メッセージの作成、メッセージのハッシュ化

$echo "secret" > message.txt
$ cat message.txt
secret
$ sha256sum message.txt | cut -c1-64 > hashed_message.txt
$ cat hashed_message.txt
b37e50cedcd3e3f1ff64f4afc0422084ae694253cf399326868e07a35f4a45fb

署名データの作成

$ openssl dgst -SHA256 -sign private.pem hashed_message.txt > hashed_message.sig

作成した公開鍵で署名を検証

$ openssl dgst -SHA256 -verify public.pem -signature hashed_message.sig                                                 
$ openssl dgst -SHA256 -verify public.pem -signature hashed_message.sig hashed_message.txt
Verified OK

Verified OKと表示されれば検証に成功です！

参考にさせて頂きました

cutコマンド

opensslコマンドの使い方

堅牢なスマートコントラクト開発のためのブロックチェーン［技術］入門

opensslのオプション

＄openssl -help
openssl:Error: '-help' is an invalid command.

Standard commands
asn1parse         ca                ciphers           cms               
crl               crl2pkcs7         dgst              dh                
dhparam           dsa               dsaparam          ec                
ecparam           enc               engine            errstr            
gendh             gendsa            genpkey           genrsa            
nseq              ocsp              passwd            pkcs12            
pkcs7             pkcs8             pkey              pkeyparam         
pkeyutl           prime             rand              req               
rsa               rsautl            s_client          s_server          
s_time            sess_id           smime             speed             
spkac             srp               ts                verify            
version           x509              

Message Digest commands (see the `dgst' command for more details)
md4               md5               rmd160            sha               
sha1              

Cipher commands (see the `enc' command for more details)
aes-128-cbc       aes-128-ecb       aes-192-cbc       aes-192-ecb       
aes-256-cbc       aes-256-ecb       base64            bf                
bf-cbc            bf-cfb            bf-ecb            bf-ofb            
camellia-128-cbc  camellia-128-ecb  camellia-192-cbc  camellia-192-ecb  
camellia-256-cbc  camellia-256-ecb  cast              cast-cbc          
cast5-cbc         cast5-cfb         cast5-ecb         cast5-ofb         
des               des-cbc           des-cfb           des-ecb           
des-ede           des-ede-cbc       des-ede-cfb       des-ede-ofb       
des-ede3          des-ede3-cbc      des-ede3-cfb      des-ede3-ofb      
des-ofb           des3              desx              rc2               
rc2-40-cbc        rc2-64-cbc        rc2-cbc           rc2-cfb           
rc2-ecb           rc2-ofb           rc4               rc4-40            
seed              seed-cbc          seed-cfb          seed-ecb          
seed-ofb          

dgstのオプション

$ openssl dgst -h
unknown option '-h'
options are
-c              to output the digest with separating colons
-r              to output the digest in coreutils format
-d              to output debug info
-hex            output as hex dump
-binary         output in binary form
-hmac arg       set the HMAC key to arg
-non-fips-allow allow use of non FIPS digest
-sign   file    sign digest using private key in file
-verify file    verify a signature using public key in file
-prverify file  verify a signature using private key in file
-keyform arg    key file format (PEM or ENGINE)
-out filename   output to filename rather than stdout
-signature file signature to verify
-sigopt nm:v    signature parameter
-hmac key       create hashed MAC with key
-mac algorithm  create MAC (not neccessarily HMAC)
-macopt nm:v    MAC algorithm parameters or key
-engine e       use engine e, possibly a hardware device.
-md4            to use the md4 message digest algorithm
-md5            to use the md5 message digest algorithm
-ripemd160      to use the ripemd160 message digest algorithm
-sha            to use the sha message digest algorithm
-sha1           to use the sha1 message digest algorithm
-sha224         to use the sha224 message digest algorithm
-sha256         to use the sha256 message digest algorithm
-sha384         to use the sha384 message digest algorithm
-sha512         to use the sha512 message digest algorithm
-whirlpool      to use the whirlpool message digest algorithm