Compute SES SMTP password from AWS secret key

ses_smtp_password.rb

#!/usr/bin/env ruby

require 'openssl'
require 'base64'

key = ARGV[0]
message = 'SendRawEmail'
version = 0x02

digest = OpenSSL::Digest.new('sha256')
signature = OpenSSL::HMAC.digest(digest, key, message)

signature_and_version = version.chr + signature
smtp_password = Base64.encode64(signature_and_version)

puts "smtp password:\n#{smtp_password}"