RSA加密法python实现

首先，公钥私钥生成文件代码在这儿：https://blog.csdn.net/qq_41938259/article/details/86765012

这是加密前的原a文：As God as my witness...as god as my witness they’re not going to lick me.I’m going to live throughthis and when it’s all over, I’ll never be hungry again.No,nor any of my folk . If I have to lie , steal,cheat,or kill, as God as my witness,I’ll never be hungry again.------Gone with the wind

先给出I/O示例： RSA加密法python实现

RSA加密法python实现

以下给出代码和实现，自以为注释十分详细了：

import sys

DEFAULT_BLOCK_SIZE=128#默认区块大小128bytes
BYTE_SIZE=256#默认1byte有256种不同的值

def main():
    filename = 'encrypted_file.txt'
    mode=input('输入E为加密，输入D为解密：').lower()
    if mode=='e':
        try:
            message=open(filename).read()
        except IOError:
            print('文件打开失败。')
        else:
            pubKeyFilename='al_sweigart_pubkey.txt'
            print('加密......')
            encryptedText=encryptAndWriteToFile(filename,pubKeyFilename,message)
            print('加密文件内容：')
            print(encryptedText)
    elif mode=='d':
        privKeyFilename='al_sweigart_privkey.txt'
        print('解密......')
        try:
            decryptedText=readFromFileAndDecrypt(filename,privKeyFilename)
        except IOError:
            print('文件打开失败。')
        else:
            print('解密文件名内容：')
            print(decryptedText)

#getBlocksFromText()函数接受message返回一个表示它的列表，其元素为区块
def getBlocksFromText(message,blockSize=DEFAULT_BLOCK_SIZE):
    messageBytes=message.encode('ascii')#转为ASCII码对应的数字
    blockInts=[]
    #for循环创建大整数，最终保存到blockInt里
    for blockStart in range(0,len(messageBytes),blockSize):
        blockInt=0
        for i in range(blockStart,min(blockStart+blockSize,len(messageBytes))):
            blockInt+=messageBytes[i]*(BYTE_SIZE**(i%blockSize))
        blockInts.append(blockInt)
    #返回的是blockInts列表而不是blockInt大数
    return blockInts

#将区块列表转化为原始字符串
def getTextFromBlocks(blockInts,messageLength,blockSize=DEFAULT_BLOCK_SIZE):
    message=[]
    for blockInt in blockInts:
        blockMessage=[]
        for i in range(blockSize-1,-1,-1):
            if len(message)+i<messageLength:
                asciiNumber=blockInt//(BYTE_SIZE**i)
                blockInt=blockInt%(BYTE_SIZE**i)
                blockMessage.insert(0,chr(asciiNumber))
        message.extend(blockMessage)
    return ''.join(message)

def encryptMessage(message,key,blockSize=DEFAULT_BLOCK_SIZE):
    encryptedBlocks=[]
    n,e=key
    for block in getBlocksFromText(message,blockSize):
        #下面的运算是block^e mod n
        encryptedBlocks.append(pow(block,e,n))
    return encryptedBlocks

#dexryptMessage保存解密的整数区块列表，key则通过多重赋值给n和d
def decryptMessage(encryptedBlocks,messageLength,key,blockSize=DEFAULT_BLOCK_SIZE):
    decryptedBlocks=[]
    n,d=key
    for block in encryptedBlocks:
        #对之前的block^e mod n运算解密
        decryptedBlocks.append(pow(block,d,n))
        return getTextFromBlocks(decryptedBlocks,messageLength,blockSize)

#从**文件读取公钥和私钥
#格式：**大小整数，n的大整数，e或d的大整数
#split()根据逗号分割，以字符串格式保存到content变量里
def readKeyFile(keyFilename):
    fo=open(keyFilename)
    content=fo.read()
    fo.close()
    keySize,n,EorD=content.split(',')
    return(int(keySize),int(n),int(EorD))

#函数接受三个参数，分别是写入加密消息的文件名，需要的公钥文件名，和钥加密的消息
def encryptAndWriteToFile(messageFilename,keyFilename,message,blockSize=DEFAULT_BLOCK_SIZE):
    #读取公钥和私钥
    keySize, n, e = readKeyFile(keyFilename)

    #确认大小无误
    if keySize < blockSize * 8:  # 一个区块8比特
        sys.exit(
            'ERROR: Block size is %s bits and key size is %s bits. The RSA cipher requires the block size to be equal to or greater than the key size. Either decrease the block size or use different keys.' % (
            blockSize * 8, keySize))

    #加密过程
    encryptedBlocks = encryptMessage(message, (n, e), blockSize)

    # 将大数字转为字符串
    for i in range(len(encryptedBlocks)):
        encryptedBlocks[i] = str(encryptedBlocks[i])
    encryptedContent = ','.join(encryptedBlocks)

    #写入txt文件
    encryptedContent = '%s_%s_%s' % (len(message), blockSize, encryptedContent)
    fo = open(messageFilename, 'w')
    fo.write(encryptedContent)
    fo.close()
    #并返回加密内容至屏幕
    return encryptedContent

#函数两个参数分别是密文文件和**信息
def readFromFileAndDecrypt(messageFilename, keyFilename):
    keySize, n, d = readKeyFile(keyFilename)

    #解密过程
    fo = open(messageFilename)
    content = fo.read()
    messageLength, blockSize, encryptedMessage = content.split('_')
    messageLength = int(messageLength)
    blockSize = int(blockSize)

    # Check that key size is greater than block size.
    if keySize < blockSize * 8:  # * 8 to convert bytes to bits
        sys.exit(
            'ERROR: Block size is %s bits and key size is %s bits. The RSA cipher requires the block size to be equal to or greater than the key size. Did you specify the correct key file and encrypted file?' % (
            blockSize * 8, keySize))

    # 将密文转为大数字
    encryptedBlocks = []
    for block in encryptedMessage.split(','):
        encryptedBlocks.append(int(block))

    # 返回解密结果
    return decryptMessage(encryptedBlocks, messageLength, (n, d), blockSize)

if __name__ == '__main__':
    main()

RSA加密法python实现

相关推荐