B4X Requires Chilkat v11.0.0+

Get EC Public Key from EC Private Key

See more ECC Examples

Demonstrates how to get an EC public key from an EC private key. B4X

Dim success As Boolean = False

'  We have an ECC private key...
'  The contents of the private key PEM file look like this:

'  	-----BEGIN PRIVATE KEY-----
'  	MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQg3J8q/24D1sEKGdP9
'  	72MGYElLGpw/a56Y3t6pfON3uhShRANCAATlSmoizyhAwoYZAOuFBATl07/1RR54
'  	a1Dzfm16grxJe666AGKR+bSs24hk7TEpaeCTvT8YOOM3l+xKFg7zq6Q9
'  	-----END PRIVATE KEY-----

Dim privKey As ChilkatPrivateKey
privKey.Initialize("privKey")
success = privKey.LoadPemFile("qa_data/ecc/secp256r1-key-pkcs8.pem")
If success = False Then
    Log(privKey.LastErrorText)
    Return
End If


'  Get the public key.
Dim pubKey As ChilkatPublicKey
pubKey.Initialize
privKey.ToPublicKey(pubKey)

'  Save the public key to a PEM file.
success = pubKey.SavePemFile(False, "qa_data/ecc/secp256r1-pubkey.pem")
If success = False Then
    Log(pubKey.LastErrorText)
    Return
End If


'  The contents of the ECC public key PEM file look like this:

'  	-----BEGIN PUBLIC KEY-----
'  	MIIBSzCCAQMGByqGSM49AgEwgfcCAQEwLAYHKoZIzj0BAQIhAP////8AAAABAAAA
'  	AAAAAAAAAAAA////////////////MFsEIP////8AAAABAAAAAAAAAAAAAAAA////
'  	///////////8BCBaxjXYqjqT57PrvVV2mIa8ZR0GsMxTsPY7zjw+J9JgSwMVAMSd
'  	NgiG5wSTamZ44ROdJreBn36QBEEEaxfR8uEsQkf4vOblY6RA8ncDfYEt6zOg9KE5
'  	RdiYwpZP40Li/hp/m47n60p8D54WK84zV2sxXs7LtkBoN79R9QIhAP////8AAAAA
'  	//////////+85vqtpxeehPO5ysL8YyVRAgEBA0IABOVKaiLPKEDChhkA64UEBOXT
'  	v/VFHnhrUPN+bXqCvEl7rroAYpH5tKzbiGTtMSlp4JO9Pxg44zeX7EoWDvOrpD0=
'  	-----END PUBLIC KEY-----

Log("Success.")