You should not be using DES. You should not have been using DES for the
past 30 years.
The ed DES scheme lacked several desirable properties of a sealed
document system, even ignoring DES itself. In particular, it did not
provide the "integrity" cryptographic property (detection of tampering), and
it treated ASCII passwords as 64-bit keys (instead of using a KDF like
scrypt or PBKDF2).
Some general approaches ed(1) users might consider to replace the removed
DES mode:
- Full disk encryption with something like AES-XTS. This is easy to
conceptualize, design, and implement, and it provides confidentiality for
data at rest. Like ECB, it lacks tampering protection. Examples include
GELI, LUKS, FileVault2.
- Encrypted overlay ("stackable") filesystems (EncFS, PEFS?, CryptoFS,
others).
- Native encryption at the filesystem layer. Ext4/F2FS, ZFS, APFS, and
NTFS all have some flavor of this.
- Storing your files unencrypted. It's not like DES was doing you much
good.
If you have DES-ECB scrambled files produced by ed(1) prior to this change,
you may descrypt them with:
openssl des-cbc -d -iv 0 -K <key in hex> -in <inputfile> -out <plaintext>