Big file encryption

big_file_encryption.bash

# 秘密鍵を作成する(パスフレーズ有り)
openssl genrsa -aes256 4096 > private.key

# X.509 証明書生成 (自己署名証明書)
openssl req -new -x509 -key private.key -out cert.pem -days 36500 -subj /CN="sample"

# 証明書情報の確認
openssl x509 -noout -subject -dates -in cert.pem

# 暗号化
openssl smime \
     -encrypt \
     -binary \
     -aes-256-cbc \
     -in largefile.bin \
     -out largefile.bin.encrypted \
     -outform DER \
     cert.pem

# 復号化
openssl smime \
  -decrypt \
  -in largefile.bin.encrypted \
  -binary \
  -inform DER \
  -inkey private.key \
  -out largefile.bin.dat.decrypted