Here is a 150 word summary of the blog post:

The blog post demonstrates how to use AWS Key Management Service (KMS) for encryption and decryption. It first explains encryption terminology like plaintext, ciphertext, and keys. It then walks through creating a KMS key, generating custom encryption key material locally using OpenSSL, encrypting the key material with the KMS wrapping key, and importing the encrypted key material into KMS. With the custom KMS key configured, the post shows examples of encrypting and decrypting a text file with the AWS CLI using the KMS key. It also demonstrates deleting and re-importing key material to disable and re-enable decryption. Finally, it explains the concept of envelope encryption by having KMS generate a data key, using the data key to encrypt data outside of KMS, storing the encrypted data key alongside the ciphertext, and later having KMS decrypt the data key to decrypt the data.