Elgamal

Implementation of Elgamal algorithm in Golang, based on these series of videos (the parameter nomenclature is based on them).

Public and private keys are composed of 3 elements each:

Kpub = (p, alfa, B)
Kpriv = (p, alfa, b)

These parameters are:

p (parameter --p): A random integer
alfa (parameter --alfa): A generator of Zp
b (parameter --b): A secret integer between 2 and (p-2)
B (parameter --B): A public modular exponentiation calculated as B = (alfa^(b))mod(p)

Encryption

For the encryption process, it is necessary to add --encrypt, the parameters of the public key (--p, --alfa and --B) and the plaintext message (parameter --m). The verbose parameter (--debug) is optional:

go run elgamal.go --encrypt --p=79 --alfa=30 --B=59 --m=44 --debug

Decryption

For the decryption process, it is necessary to add --decrypt, the parameters of the private key (--p, --alfa and --b), the encrypted message (parameter --m) and the ephemeral key received with the message (--Ke). The verbose parameter (--debug) is optional:

go run elgamal.go --decrypt --p=79 --alfa=30 --b=61 --m=73 --Ke=13 --debug

Signature

For the signing process, it is necessary to add --sign, the parameters of the private key (--p, --alfa and --b) and the plaintext message (parameter --m). The verbose parameter (--debug) is optional:

go run elgamal.go --sign --p=541 --alfa=128 --b=105 --m=95 --debug

Signature verification

For the signature verification process, it is necessary to add --verify, the parameters of the public key (--p, --alfa and --B), the plaintext message (parameter --m) and the signature parameters (--r and --s). The verbose parameter (--debug) is optional:

go run elgamal.go --verify --p=541 --alfa=128 --B=239 --m=95 --r=280 --s=65 --debug

Note