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@silicakes
Last active October 2, 2022 06:34
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NodeJS Crypto custom padding example
// Following an answer I posted to my question here:
// http://stackoverflow.com/questions/21856892/node-crypto-aes256-cbc-0x0-padding-example/21858749#21858749
//I'm expecting a utf8 encoded string
function customPadding(str, blockSize, padder, format) {
str = new Buffer(str,"utf8").toString(format);
//1 char = 8bytes
var bitLength = str.length*8;
if(bitLength < blockSize) {
for(i=bitLength;i<blockSize;i+=8) {
str += padder;
}
} else if(bitLength > blockSize) {
while((str.length*8)%blockSize != 0) {
str+= padder;
}
}
return new Buffer(str, format).toString("utf8");
}
function encrypt(str) {
var cipher = crypto.createCipheriv('aes-256-cbc', key, iv).setAutoPadding(false);
str = customPadding(str, 256, 0x0, "hex"); // magic happens here
var crypt = cipher.update(str, 'utf8', 'base64');
crypt += cipher.final("base64");
return crypt;
}
var t = encrypt("dude");
@gtsigner
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thanks

@chungguo
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chungguo commented Jun 3, 2019

thanks

@dusblinov
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thanks!

@qixuezheng
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You're awesome! Thank you!

@richlewis14
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richlewis14 commented Jun 23, 2021

Hey, thank you for posting this. Im facing an issue where my padding needs to be 0x0001 (KCS7Padding) on the decryption side, would this example work for this?

@silicakes
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Hey, thank you for posting this. Im facing an issue where my padding needs to be 0x0001 (KCS7Padding) on the decryption side, would this example work for this?

It should, go ahead and try it.

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