security dump-keychain -d login.keychain

keychain: "/Users/<username>/Library/Keychains/login.keychain"
class: "inet"
attributes:
    0x00000007 <blob>="tech.slashdot.org (<username for this web login>)"
    0x00000008 <blob>=<NULL>
    "acct"<blob>="<username for this web login>"
    "atyp"<blob>="form"
    "cdat"<timedate>=0x32303038303432333038323730355A00  "20080423082705Z00"
    "crtr"<uint32>=<NULL>
    "cusi"<sint32>=<NULL>
    "desc"<blob>="Kennwort des Web-Formulars"
    "icmt"<blob>="default"
    "invi"<sint32>=<NULL>
    "mdat"<timedate>=0x32303038303432333038323730355A00  "20080423082705Z00"
    "nega"<sint32>=<NULL>
    "path"<blob>=<NULL>
    "port"<uint32>=0x00000000
    "prot"<blob>=<NULL>
    "ptcl"<uint32>="http"
    "scrp"<sint32>=<NULL>
    "sdmn"<blob>=<NULL>
    "srvr"<blob>="tech.slashdot.org"
    "type"<uint32>=<NULL>
data:
"<the plaintext password for this key>"

sudo security dump-keychain -d login.keychain