Use correct envvar names.
#!/bin/bash
set -eu
docker login -u "${DOCKER_USERNAME}" -p "${DOCKER_PASSWORD}"
-openssl aes-256-cbc -K $encrypted_c6b45058ffe8_key -iv $encrypted_c6b45058ffe8_iv -in travis.enc -out travis -d
+openssl aes-256-cbc -K $encrypted_d8355cc3d845_key -iv $encrypted_d8355cc3d845_iv -in travis.enc -out travis -d
set -x
chmod 0400 travis
export GIT_SSH_COMMAND="ssh -i ${PWD}/travis"
