Fwd: public/private keys.... what are they?

Mon Feb 16 20:55:07 MST 2015

Please tell me of the accuracy of this statement:
You don't run the keys on emails rather you run the keys over data you may
send as an attachment.

:-)~MIKE~(-:

On Mon, Feb 16, 2015 at 8:35 PM, Stephen Partington <cryptworks at gmail.com>
wrote:

> The public key is meant to be available to sign data for that person. you
> do this so they can un-encrypt the data but they know it was signed. and
> only they can un-encrypt that data.
>
> On Mon, Feb 16, 2015 at 8:28 PM, Michael Havens <bmike1 at gmail.com> wrote:
>
>> That is where I was befuddled. I didn't realize that the public/private
>> keys belonged to the same person. So when we get a message with a key on it
>> that is the public key and everyone has access to it and that will
>> encrypt/decrypt a message if we know how to use it.. And then originator of
>> the key has the private key to do the opposite as was done to the message
>> before it was sent.
>>
>> :-)~MIKE~(-:
>>
>> On Mon, Feb 16, 2015 at 8:18 PM, Stephen Partington <cryptworks at gmail.com
>> > wrote:
>>
>>> Stolen but relevant.
>>>
>>> The Public and Private key pair comprise of two uniquely related
>>> cryptographic keys (basically long random numbers). Below is an example of
>>> a Public Key:
>>>
>>> 3048 0241 00C9 18FA CF8D EB2D EFD5 FD37 89B9 E069 EA97 FC20 5E35 F577
>>> EE31 C4FB C6E4 4811 7D86 BC8F BAFA 362F 922B F01B 2F40 C744 2654 C0DD 2881
>>> D673 CA2B 4003 C266 E2CD CB02 0301 0001
>>>
>>> The Public Key is what its name suggests - Public. It is made available
>>> to everyone via a publicly accessible repository or directory. On the other
>>> hand, the Private Key must remain confidential to its respective owner.
>>>
>>> Because the key pair is mathematically related, whatever is encrypted
>>> with a Public Key may only be decrypted by its corresponding Private Key
>>> and vice versa.
>>>
>>> For example, if Bob wants to send sensitive data to Alice, and wants to
>>> be sure that only Alice may be able to read it, he will encrypt the data
>>> with Alice's Public Key. Only Alice has access to her corresponding Private
>>> Key and as a result is the only person with the capability of decrypting
>>> the encrypted data back into its original form.
>>>
>>> As only Alice has access to her Private Key, it is possible that only
>>> Alice can decrypt the encrypted data. Even if someone else gains access to
>>> the encrypted data, it will remain confidential as they should not have
>>> access to Alice's Private Key.
>>>
>>> From
>>> https://www.comodo.com/resources/small-business/digital-certificates2.php
>>> On Feb 16, 2015 7:57 PM, "Michael Havens" <bmike1 at gmail.com> wrote:
>>>
>>>> no.... no..... Joseph says it is like two locks.When you unlock one you
>>>> lock the other? hmmmm....
>>>>
>>>> :-)~MIKE~(-:
>>>>
>>>> On Mon, Feb 16, 2015 at 7:49 PM, Michael Havens <bmike1 at gmail.com>
>>>> wrote:
>>>>
>>>>> and then the public key everyone can see and the private one only you
>>>>> can see?
>>>>>
>>>>> :-)~MIKE~(-:
>>>>>
>>>>> On Mon, Feb 16, 2015 at 7:45 PM, Michael Havens <bmike1 at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> is a real simplified version that it is like two locks locked
>>>>>> together and each key opens one of the locks?
>>>>>>
>>>>>> :-)~MIKE~(-:
>>>>>>
>>>>>> On Mon, Feb 9, 2015 at 7:05 PM, Joseph Sinclair <
>>>>>> plug-discussion at stcaz.net> wrote:
>>>>>>
>>>>>>> Lots of confusion here.  Let me try to clarify (a small amount).
>>>>>>>
>>>>>>> Background:
>>>>>>> "Public Key" cryptography is also called "Asymmetric Cryptography".
>>>>>>> The reason is that there are two different keys, and they only work
>>>>>>> together in an "asymmetric" fashion (whatever one key does, the other key
>>>>>>> undoes).
>>>>>>> The keys are "related" mathematically, but it is (currently) not
>>>>>>> possible to figure out one key from the other (so having a public key does
>>>>>>> not help you determine the private key).
>>>>>>>
>>>>>>> 1) There are two keys.
>>>>>>>   a) There are also two *actions*, encryption (hiding content from
>>>>>>> unauthorized viewers) and verification (proving a message is authentic and
>>>>>>> from a known entity).
>>>>>>> 2) *Either* key can be used to encrypt, but the *other* key is
>>>>>>> needed to decrypt.
>>>>>>>   a) that means public(encrypt) ==> private(decrypt) *or*
>>>>>>> private(encrypt) ==> public(decrypt).
>>>>>>>   b) a single key cannot both encrypt and decrypt the same message
>>>>>>> (That's why it's called "asymmetric encryption", the keys are *not*
>>>>>>> interchangeable).
>>>>>>> 3) The "Public" key  is meant to be published far and wide.  It is
>>>>>>> used to encrypt a message intended for the key "owner", and it is also used
>>>>>>> (by decrypting a hash) to "verify" that a message was sent by the real
>>>>>>> owner (signature).
>>>>>>> 4) The "Private" key is meant to be kept strictly secret.  It can
>>>>>>> decrypt any message encrypted by the public key.  It can also encrypt a
>>>>>>> message that only the "Public" key can decrypt (see signature below).
>>>>>>>
>>>>>>> Encryption is the function most people understand (it's also very
>>>>>>> rarely used**).  You encrypt a message using the "Public" key as the
>>>>>>> encryption key.
>>>>>>> Once encrypted the data is essentially static to anyone who does not
>>>>>>> possess the "Private" key.
>>>>>>> There are a ton of details involved, so it's rarely explained
>>>>>>> further than that without reading an entire textbook (or 3).
>>>>>>>
>>>>>>> There is a *related* function called "verification" or "Digital
>>>>>>> Signature".  This is used to prove (without ever exposing a secret) that a
>>>>>>> particular entity possesses the secret "Private" key.
>>>>>>> This is how you know your HTTPS connection is connected to the
>>>>>>> correct endpoint rather than some imposter (it's also how ssh passwordless
>>>>>>> login works).
>>>>>>> This involves (very simplified) using the "Private" key to encrypt
>>>>>>> the hash of a message (to sign the message) or a "nonce" value (to verify
>>>>>>> endpoint identity, e.g. SSL).
>>>>>>> Once the value (hash or nonce) is encrypted by the "Private" key,
>>>>>>> only the matching "Public" key will decrypt it.
>>>>>>> So if someone sent you a message and it's encrypted hash, then you
>>>>>>> decrypt the hash with the "Public" key, and if it decrypts correctly you
>>>>>>> know it is valid.
>>>>>>> Of course, you would also hash the message (there are standard
>>>>>>> algorithms for generating these "hash" values) and see if your results
>>>>>>> match what you decrypted (if they don't, then the message isn't what the
>>>>>>> sender meant to send).
>>>>>>>
>>>>>>> There are several ways of implementing assymetric cryptography, the
>>>>>>> most commonly used is with the RSA family of algorithms.
>>>>>>> The "elliptic curve" (or "EC") family of algorithms have grown in
>>>>>>> popularity in recent years, but are still only occasionally used.
>>>>>>> The two are mostly different in the mathematics behind how and why
>>>>>>> they work.
>>>>>>> The basic concepts (two keys, two operations, what one key does the
>>>>>>> other undoes) are the same.
>>>>>>>
>>>>>>> Hopefully that helps a bit.
>>>>>>>
>>>>>>> Public Key Cryptography (and Asymmetric Cryptography in general) is
>>>>>>> a huge and complex topic, so I second Todd's suggestion that if you want to
>>>>>>> really understand this, you will want to read a few good textbooks on the
>>>>>>> subject.
>>>>>>>
>>>>>>> ==Joseph++
>>>>>>>
>>>>>>> ** Some will say that SSL uses public key encryption.  This is true,
>>>>>>> but misleading, because the public key encryption is only used during the
>>>>>>> "handshake" where the SSL connection is setup to encrypt the exchange of
>>>>>>> symmetric keys.  This "key exchange" is what Diffie and Helman invented
>>>>>>> that makes modern PKI possible.
>>>>>>> The encryption that does all the heavy lifting of keeping the SSL
>>>>>>> tunnel secure is always a "block" (symmetric) algorithm, most commonly AES
>>>>>>> (for modern systems where security is properly implemented) or 3DES
>>>>>>> (slightly older but still pretty secure) or RC4 (completely insecure and
>>>>>>> used by extremely badly managed sites running ancient and horribly flawed
>>>>>>> web server software, unfortunately there are still far too many very large
>>>>>>> businesses that do this).
>>>>>>>
>>>>>>>
>>>>>>> On 02/09/2015 06:01 PM, Michael Havens wrote:
>>>>>>> > helps some but you state:
>>>>>>> >
>>>>>>> > you want others to be able to check that you actually
>>>>>>> > sent the message (by using your public key)
>>>>>>> >
>>>>>>> > Where do they get your public key?
>>>>>>> > How does your public key and private key decrypt when it seems the
>>>>>>> public
>>>>>>> > key changes.
>>>>>>> >
>>>>>>> > :-)~MIKE~(-:
>>>>>>> >
>>>>>>> > On Mon, Feb 9, 2015 at 5:48 PM, someone wrote:
>>>>>>> >
>>>>>>> >> So if I'm right calling it a 'key' is a misnomer. I am a very
>>>>>>> literal
>>>>>>> >> person. if they call it a key it unlocks things, not creates them.
>>>>>>> >> That is where my confusion is from. Am I correct?
>>>>>>> >>
>>>>>>> >> Not quite correct...
>>>>>>> >>
>>>>>>> >> Both the public and private keys ARE keys... they're just used a
>>>>>>> >> little differently.
>>>>>>> >>
>>>>>>> >> You keep your private key secure, and use it to digitally sign a
>>>>>>> >> message when you want others to be able to check that you actually
>>>>>>> >> sent the message (by using your public key). Others can send an
>>>>>>> >> encrypted message that only you can decode, by encrypting the
>>>>>>> message
>>>>>>> >> using your public key. When you get the message, you can use your
>>>>>>> >> private key to undo the encryption that was done using your public
>>>>>>> >> key.
>>>>>>> >>
>>>>>>> >> So, in a way, the public and private keys can be thought of as two
>>>>>>> >> pieces of a single, combined key. The software that does the
>>>>>>> signing
>>>>>>> >> or encryption (using the keys), such as gnupg, pgp, etc., is more
>>>>>>> like
>>>>>>> >> the lock that the keys fit.
>>>>>>> >>
>>>>>>> >> I hope that helps.
>>>>>>> >> --
>>>>>>> >> Kevin O'Connor
>>>>>>> >>
>>>>>>> >
>>>>>>> >
>>>>>>> >
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>>>>>>> >
>>>>>>>
>>>>>>>
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>>>>>>
>>>>>>
>>>>>
>>>>
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>
>
>
> --
> A mouse trap, placed on top of your alarm clock, will prevent you from
> rolling over and going back to sleep after you hit the snooze button.
>
> Stephen
>
>
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